I agree with N2L that you should call a 24 hour health line - there are a few and your health fund may have one if you have PHI. Always better to be safe than sorry, and you'll only worry yourself silly until she wakes up and is her "normal" self.

Otherwise, I'm sure its absolutely nothing and just another one of those things that drives mums with new bubs up the wall with worry and second guessing. I'm pretty much put the house on her just having a big sleepy afternoon and unfortunately you're probably going to pay for it when she does wake up with LOTS of feeding to catch up on what she's missed during her sleepy period. FWIW, A has been screaming all morning (from 10am until 1.30 pm). She is now asleep and I don't expect (read hope!) to hear from her for at least another couple of hours. I also had to wake her yesterday morning to feed her because we had to go out - she had been sleep for 5 hours and it was an extremely half hearted 3 minute feed.

Try not to stress, give the nurse a call, and when you're reassured its all good take the opportunity to put your feet up and enjoy being hands free for a while. Hang in there. I promise all the second guessing does ease.