There were at least two other comics out today with New Year's Impositions in the gag - one of them was 'Momma', which I think (not sure) is in the re-run mode... So this may not have been a new concept after all - or it may have been a trend-setter!
And look at the neatly spread blanket. As any other person, Dilbert turned few times during sleep and the blanket shall be wrinkled, unless .... someone just got up and straitened the blanket .... ???
Did you notice that in the first panel there is a second pillow besides Dilbert's, but it is gone in the next panels? Maybe "other people" refered to the person (Amber???) who used that pillow?
(Sorry, I was wathching too many Poirots and Maigrets lately.)