I don't have a very large social circle IRL. I don't see my high school friends a lot but they're all the same age so that's not very interesting. My roommates are my age (went to high school with him) and 18 though, so there's a gap though. 18-year-old feels just as old as I am so it rarely weirds me out or anything... but sometimes I feel so old if we end up talking about TV shows we watched as kids or something. For the most part, though, age has never been an issue for me. My friends do tend to be younger if anything, though.
Most of the other friends I make at school are younger than me by a year or two (because I'm behiiind), though one guy was my age, I think. (Graduated this year though, aww.)