I don't think it makes you a slut, but I don't think it's right either. I'm assuming that this is the first time you met both of them, and I don't think anyone should make out with anyone the first time they meet.(although i'm probably the exception in thinking this) But no, you are most definately not a slut. At least not for this, maybe a little slutty, but not a slut. I think there's a difference. anyway, I'm gonna stop now because I lost interest in completing my thought.
.