Is it weird or is it just me who feels weird about it

So I 27f have a friend 33m and he lives with a roommate. His roommate is like, middle to late 40s. I went over to my friends house the other day and his roommate had some of his friends there. They looked super young, so I asked my friend how old these guys were. I was shocked to find out the youngest one was 19 and the oldest was barely 21. Am I weird for finding it uncomfortable for a man as old as 40 something years old to have these younger "friends"? Personally as a 27f I wouldn't have much in common with a female that's 19. Only thing in common would be partying. But with such a young crowd? I don't know. It felt weird to me. "Red flag"-ish. It's none of my business who his roommate hangs out with but I'm just curious to what others think about it.