There are lots of reasons it might have happened, so it is impossible to know apart from more details.
Myron/chrism is a sign of communion with the bishop. In eastern churches, the bishop is usually the Patriarch. Myron is usually only consecrated by the Patriarch when needed, and distributed throughout the Church. The Ecumenical Patriarch uses a complex formula of 37 aromas that are combined over seceral days in Holy Week before consecration on Holy Thursday.
Catholics, by contrast, is consecrated by every ordinary bishop every year at a Chrism Mass on Holy Thursday, or thereabouts. The formula is the simple addition of balsam to olive oil, done during the Mass itself. From there it is distributed throughout the diocese.
From there, differences developed. Re-chrismation may be done on converting from one Church to another, as a sign of union not just with Christ the Anointed One but also of union with the new Patriarch. Catholics are always united with the Pope, so there is no need for a new chrismation. Even an Orthodox chrismation is considered valid, because it is within the one Church headed by the Pope.
Beyond that, myron can sometimes be used like Holy Water, a reaffirmation of the original rite that often happened in infancy. The anointing is not a repetition, but a remembering.
And because there are many jurisdictions, there are probably even more reasons particular to different Churches. I am just trying to give you a sense of possible differences, which can vary widely.