I'm normally like, cool I get to go! Like I love that I get a free ticket, or someone has one. If my best friend got everyone else a ticket, and left me out, then I was the fallback, obviously I'd be offended. I don't need to be high up on everyone's list though. And say my best friend was going with another friendship group of his who I didn't know as well, then I wouldn't be offended to not be invited. Like unless I see any ill intent, it's a whatever issue.
On the topic, last minute invites mean nothing. Just means you won't part of the core organising group. Which pretty much tends to be the few people who came up with the idea to have dinner and get people together. At least with my friends, things seem to grow from there, not always in any organised fashion. They may not have wanted your friend along who knew no one, or they may not have had enough places, or any number of reasons. If they hated you or didn't want you there though, they wouldn't have bothered with the invite and just gone ahead without even letting you know.