Randomly not invited on friends trip and not sure how to feel or react
Me and my 7 buddies have been really close friends since we were young, growing up in the same state and going to the same schools, joining the same sports teams and whatnot. Now that we are in college and some have moved out of state we obviously aren't as close but we still talk quite frequently, game together and get together with whoever is still around quite often.
Recently 2/3 that are at out of state colleges came back for a couple weeks this summer and we hung out a bit, but I came to find out that 4 of them had gone on a road trip down the coast together to one of their parents summer homes (one of the ones from out of state). The other three that didn't go were either still out of state, travelling in europe and my last buddy is working full time, so thinking about it I was the only one that could've also gone but I never heard about it/wasn't invited. It just seems so random, as I've been invited and done this trip with them before, but for some reason I was just left off this trip.
This past week we've been all hanging out again (not including the buddy whose place it was as he returned to get ready for next semester) and my friends are openly talking about the trip, making inside jokes that they obviously came up with eachother during the time, but no one is addressing that I didn't go/wasn't invited. I feel awkward when they do and it feels like they don't know I wasn't invited and are assuming I was busy or said no. I'm not on bad terms with my buddy whose place it is, we hangout whenever he's in town, we were just chatting last month cause I wished him a happy bday personally and last year I visited him in Florida cause I was down near his college last year and hungout for like a week just him and I.
It makes me feel super self-conscious that out of everyone who could've gone/been invited I was the only one who wasn't. I don't even know if this is something to bring up or how I would, I feel like just letting it pass by would be the best option because I seem to be the only one who even recognizes it. There hasn't been awkwardness at all in our friendship or hangouts since so it feels like its just this thing inside me only, and I should just ignore it.