So, every so often, I'll open up my sleeping 13" rMBP and the screen will be black. I've seen some threads on this around the web. A few times, I've done a hard reset of the machine, but recently I've noticed that if I wait 30 seconds or so, the screen will turn on and be fine. This usually only happens after being asleep for awhile. There also seems to be a correlation with a backup to my Time Capsule initiating at the same time I open the machine because once the screen turns on I see the Time Machine icon spinning. I wonder if it's a bug with Power Nap and backups while sleeping. Anyone else notice this?