I was thinking the same thing but maybe it's a gate space issue as an hour later would put it smack in the middle of the east coast/Hawaii bank of flights. Continental doesn't have departures between 0755 and 1225 so an 0845 (or even slightly later) departure would actually fill in a hole in their schedule as well for someone that may need a departure in between those hours. I'm sure the scheduling gods know something we don't. I wonder what that is?