Tummy time, nighttime version

So it looks like Baby B has discovered the joys of sleeping on her tummy. I've found her sleeping on her stomach when I woke her up the past two mornings, and I've had to flip her a couple times before I've gone to bed. I know most experts say that stomach sleeping is okay if they flip themselves to that position because that usually means they're able to turn themselves if there's a problem. Still, I can't help but be a little nervous about it since all the research points to sleeping on the back as being the most safe. I can't blame the girl, though; I can't stand sleeping on my back and find myself much more comfortable on my side or stomach.