It is a personal idiosyncrasy I have that I react immediately and poorly to errors of various types. When I see a typo or grammar error, my eyes are drawn to it. So it is during a liturgy, that my attention is grabbed by something out of the ordinary, so to speak. I dislike illicit changes in the Mass, but I am not the type to be writing letters to my bishop about it.
I have faith that my own pastor is an orthodox man, and can be trusted, along with most ministers in my parish, to carefully follow the liturgical guidelines as Rome expresses them. However, I do not have the same faith when I travel, or make a pilgrimage to some church, that I will automatically find the same type of orthodoxy. If I saw or heard something odd, no, I would not ask the priest there, because the priest is not the authority on liturgy. The bishop of a diocese is the immediate authority in these matters, but even he does not have the power to add or change things that have not been designated to him. Priests have the responsibility to read and understand current Church documents so as to follow liturgical norms, and their responsibility extends to catechesis of the faithful on matters that pertain to us. But many priests do not stay current, or do not wish to follow the rules.
In the theoretical case if I were traveling and saw a bishop do something possibly illicit then no, I would not approach him to ask about this, because charity prevails, and I did not question the validity. If I did question validity, then I might be inclined to bother the bishop.
In any case, I would feel justified to post here in the Liturgy and Sacraments forum. My anonymity here is assured, and I do not disclose my diocese or parish. There are knowledgeable people here, who know the church documents, and are happy to take the time and look things up if I do not already know where to look. In fact I had a question for Holy Week when my choir was about to do something, and I needed quick opinions on whether it was permissible. The priest could have answered this competently, but was not available in that time frame. The forum goers here provided an excellent range of responses from which I was able to determine a course of action.
I do find it upsetting that people resort to much gossip and name-calling and denigrating clergy sometimes. As a product of Catholic school, and a current Knight of Columbus, I can tell you that I have a profound respect for the very offices of deacon, priest and bishop, and personal attacks on priests are in very poor taste. (There is a current smear campaign which is not being conducted in this forum due to the moratorium, thank God for that.) But lively debate and polite disagreements are the stuff of every forum, and I am happy that CAF provides a good place like this forum for the enlightenment of the faithful such as myself.