Heather, Maybe Matt is realizing what he's lost. Maybe he's trying to understand you better and what you are dealing with. As for all of the grandparents...you know what they've been like, so you need to keep your expectation to zero and if they do something, well, then....wow!
I'm so sorry that your daughter wasn't recognized properly on her birthday...but the most important that did was you, her mother. That's what is important to her the most.
I'm going to caution you to be careful when venting to Matt. Sometimes we tend to over talk too much about things and that's when they find out things about us...unless, of course, you want him to know what's going on in your life.
Again, you can't change or control what the grandparents do. The only person you can change and/or control is you and how you deal w/them.
Enjoy the holiday weekend.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.