Yes, it’s certainly possible. And given the context, it could be true, or it could not be true. Someone could just be passingly interested in the priesthood, and then circumstances change or (hopefully) they discern that interest further, and find that God is calling them to something else. Or else that comment could be made without any real knowledge of the person, perhaps flippantly or maliciously, when it’s not a mere passing interest, but a real calling. In any event, the input of those close to someone discerning can be helpful, but it is not determining. And in either case, discernment is necessary.
A person can believe that they are being called to the priesthood but one of the signs of a genuine calling is a degree of permanence - in other words, the calling keeps coming back (if it even goes away at all) and lasts for more than just a short period of time.