I'm finding the opposite in reactions, actually (but it doesn't stop people being friends).
There's quite a number of people from working-class backgrounds. I would have never considered myself middle-class (or any other class for that matter), but apparently I'm middle-class, and sometimes people get at me over that. For example, a working class guy who tells me I have it easy because my mum pays for everything.. well actually we both get a pot of money, I just don't need to pay mine back when I'm older. When it's gone, it's gone, my mum isn't going to give me more. Oh yeah, this guy spends four times the amount I do, and that is not an exaggeration.
But really, although these things do come up, and despite what everyone says, class does come in the way for a lot of people. It's unfortunate that people don't see themselves as I did - unclassed. But hey ho.
At the end of the day though, I don't think class will be the sole reason you aren't making friends. Hell, it could just be luck.