I wouldn't even link it to the wedding, as it isn't really about that but how he regards you in general.
Definitely ask to meet him, just him and ask him to honest explain how he thinks of you!
It can either go two ways, either he holds you in the regard you deserve (high) and was being human and was unintentional, or he doesn't care at all, in which case he is a selfish arse!
Don't burn bridges though, especially for the relationship with your grandson, but definitely don't bend over backwards to help him. It would do good to say no sometimes.
We are in the same bracket as your son.
The two mothers and aunts do so much for us and our son.
We rarely manage to express our true gratitude.
Life and relationships with all members can be tricky sometimes and mostly it's the unintentional things that cause the most issues.
Life is being a busy bitch at this stage and not giving us enough time to be and process/think about anything before another problem comes along.
It doesn't mean we don't care, things just take a back burner!
We couldn't have managed without either of them. We are so indebted to them more than we can express and we'd be lost without them.
The way it is handled can make all the difference, just be open, honest and lay it before him as calmly as you can for him just to understand your perspective.
Give him some time and space to process it.