Should I be concerned that my bf doesn't invite me out with his friends anymore?

My boyfriend and I have been dating for four months now. When we first started dating he used to invite me to hang out with his friends all the time, I would usually say yes if I wasn't busy. It'd be about once a week or once every other week. Most of his friends have been acquaintances of mine for a long time so it's not like I don't know them at all. May was a very busy month for me so I rarely saw him, let alone his friends. Since then, he doesn't invite me to hang out with them at all. I get invited to the big stuff, like weddings and parties but never to hang out at the bar or anything like that. He actually seems to make it a point to not spend time with me on weds because that's the usual day they go out because of free pool. I think it would bother me less if he was just hanging out with his guy friends but it's girls too. Not only that but his friends invite other people, I know because one of my friends was invited and it wasn't even mentioned to me in passing. On the one hand, I know it's good for him to spend time with his friends without me but I also feel like I'll always be the "girlfriend" in his social circle and never a legitimate part of the group if this continues.