Having students that are older than myself in a philosophy class is usually not a problem. So far, it has never been a problem; perhaps I have been lucky in that they have all been humble enough to give me the floor. But occasionally, they do choose to argue against me, and sometimes they teach me something wonderful. I am happy with myself that, despite being a philosophy teacher, I can still recognize when a student is more knowledgable about philosophy than I am.
(This applies to my previous post; the student mentioned there is older than myself. )