Congratulations on your grandchild, and at least you know she is healthy!
I too would be dreadfully hurt by this behaviour, but as others have mentioned this is the fashion amongst new parents these days.
Seen from where I am standing, they regard their child as THEIR CHILD not as a member of a family, and as their generation focus on ME time, bonding with baby etc. this is what they are doing.
They genuinely believe they are doing what is best for the baby and for themselves in establishing a relationship with the child before admitting grandparents, aunts and uncles into the new home. And it is not something they have cooked up - they are doubtlessly following the advice of the midwife and guide books for new parents, as this is the advice given these days.
So, try to find comfort in the thought that you are not alone in being treated like this, and please, do try not to be so hurt and whatever you do, DO NOT text, e-mail or phone asking when you may see the baby!
Leaving them to get out of their new parent cocoon in their own time is the safest thing, probably, with regards to your future relationship with them.
I think I would send a card, saying so glad to hear baby is healthy, how are you? and leave it at that for now.