Abosutely under no circumstances should this happen. I am afraid that the pastor should be reported for this serious liturgical abuse. If he does not believe you, here are the appropriate citations:
From Redemptionis Sacramentum:
[64.] The homily, which is given in the course of the celebration of Holy Mass and is a part of the Liturgy itself,142 “should ordinarily be given by the Priest celebrant himself. He may entrust it to a concelebrating Priest or occasionally, according to circumstances, to a Deacon, but never to a layperson.143 In particular cases and for a just cause, the homily may even be given by a Bishop or a Priest who is present at the celebration but cannot concelebrate”.144
[65.] It should be borne in mind that any previous norm that may have admitted non-ordained faithful to give the homily during the Eucharistic celebration is to be considered abrogated by the norm of canon 767 §1.145 This practice is reprobated, so that it cannot be permitted to attain the force of custom.
[66.] The prohibition of the admission of laypersons to preach within the Mass applies also to seminarians, students of theological disciplines, and those who have assumed the function of those known as “pastoral assistants”; nor is there to be any exception for any other kind of layperson, or group, or community, or association.146
This is from Ecclesia de Mysterio, the document that predates RS by seven years:
- The homily, being an eminent form of preaching, qua per anni liturgici cursum ex textu sacro fidei mysteria et normae vitae christianae exponuntia [the Mysteries of the Faith and the guiding principles of the Christian life are expounded from the sacred text, during the course of the liturgical year],(68) also forms part of the liturgy.
The homily, therefore, during the celebration of the Holy Eucharist, must be reserved to the sacred minister, Priest or Deacon(69) to the exclusion of the non-ordained faithful, even if these should have responsibilities as “pastoral assistants” or catechists in whatever type of community or group. This exclusion is not based on the preaching ability of sacred ministers nor their theological preparation, but on that function which is reserved to them in virtue of having received the Sacrament of Holy Orders. For the same reason the diocesan Bishop cannot validly dispense from the canonical norm(70) since this is not merely a disciplinary law but one which touches upon the closely connected functions of teaching and sanctifying.
For the same reason, the practice, on some occasions, of entrusting the preaching of the homily to seminarians or theology students who are not clerics(71) is not permitted. Indeed, the homily should not be regarded as a training for some future ministry.
All previous norms which may have admitted the non-ordained faithful to preaching the homily during the Holy Eucharist are to be considered abrogated by canon 767, 1.(72)
- A form of instruction designed to promote a greater understanding of the liturgy, including personal testimonies, or the celebration of eucharistic liturgies on special occasions (e.g. day of the Seminary, day of the sick etc.) is lawful, if in harmony with liturgical norms, should such be considered objectively opportune as a means of explicating the regular homily preached by the celebrant priest. Nonetheless, these testimonies or explanations may not be such so as to assume a character which could be confused with the homily.
- As an expositional aide and providing it does not delegate the duty of preaching to others, the celebrant minister may make prudent use of “dialogue” in the homily, in accord with the liturgical norms.(73)
- Homilies in non-eucharistic liturgies may be preached by the non-ordained faithful only when expressly permitted by law and when its prescriptions for doing so are observed.
- In no instance may the homily be entrusted to priests or deacons who have lost the clerical state or who have abandoned the sacred ministry.(74)
Thus, this should not be happening at all during the Holy Sacrifice of the Mass.
Just to clarify, deacons have the faculty to preach because of Holy Orders; nuns and religious brothers (non-ordained) do not.