I do agree with you, verab, on giving it time. She could just be running late.
My POV when it comes to kids, though, is "how would I act in this situation if this were just a friend helping me with my kids?" I wouldn't be afraid to call them if they were late and find out where they are. In fact, I would find it silly NOT to call them to find out where they are. Those are my kids. They're still MY responsibility.
But if you think D13 is going to be fine watching them then the call is up to you.
Me: 32 H: 32 M 9 yrs #1 D7 #2 S5 #3 D2 Bomb 8/12/11 H moved out 8/14/11 PA started w/H & OW in 1/12 - found out 3/24/12 Got my own place 8/25/12 H & OW move in together 9/15/12 Still married.