(17M) yesterday I ran into a friend group I have whilst walking out of college. There was five of them and out of them I only really occasionally talk to three of them. 
I had fun just casually talking with them and joking, they kinda let me hang out with them despite me not being a regular in the group.
Today I was walking home and I passed two from the group (one I talk to, the other I don’t) and almost in sync they said hey and then walked past. It felt really weird as if they were trying to be funny or something, it just didn’t feel sincere

I’m now wondering whether they were just saying hi to me and I’m overthinking this whole thing or it’s something else

I usually have a problem feeling like a belong in a friend group for context as to why I’m so unsure. 

Sorry if I sound crazy or something but I’ve had a lot of friends who ghosted me as soon as they could