She had a nightmare while on the call with you? So she also fell asleep?
I dunno, to me it seems like a good sign that you're both so comfy with each other that you fall asleep on a call. I tend to have nightmares too, so I try to stay awake as long as possible (not on purpose, it's just how it is). So when I find someone that makes me feel safe enough to sleep, that's a big deal.