I'm on mat leave currently. My team had a social get together recently which I became aware of by seeing the pictures on social media. I wasn't invited. At first I assumed this was because I'm on mat leave. However someone else who is also currently on mat leave was there - and as well as being on mat leave, this person doesn't even technically work for our team anymore as she moved to a different department before she even got pregnant. Yet they saw fit to invite her. 
AIBU to feel a bit miffed and pushed out that I wasn't even asked to go?