PJCL,
My opinion is that this is not a normal operation situation and that it should not be. However, I don't know if that is how all the AZBox P+ units respond or not. Currently, I cannot test mine to find out for you as I am currently disconnected from my sat dish and I never used the SLEEP MODE when I was connected. However, I do believe that I recall someone else asking this very question a few years back.
I don't recall reading the outcome or the final solution from that experience, but I am quite certain that it occurred for someone else, too.
My opinion is that it is not a hardware failure, but something amiss in the image program itself. It sounds to me like the box isn't waking up from SLEEP MODE entirely. Some function or maybe even a power passing device is still shut down so that the tuner or maybe the LNBF power is still in an OFF condition. I am only guessing and surmising here, so take what I say with a grain of salt.
I guess the question to ask you is what firmware (image) version you currently have installed. You might try to upgrade to the most recent firmware revision (if not already there) and evaluate what happens when you come out of SLEEP MODE with that. Make sure you back up all your system settups and files and what not ahead of time so that you can go right back to this restore point.
Personally, I never have used the SLEEP MODE. Well, I think I did once, just to play with it. But, most times I just leave the AZBox running. Mine ran for five years w/o shutting down (except for when I needed to do something with power off).
RADAR