Basically, we went out for an event and then we decided to go to get dessert afterwards. I asked them if we could get back at a certain time as I had an event that would be starting at a certain time. They assured me that I would be back in time. However, by the time I did make it back, I was already 20 minutes late. It ended up being fine with the other people at the event, but still ...

Would I be the asshole for making it known I'm upset?