Why does my low oil pressure warning come on? on 2005 Chevrolet Tahoe

It comes on at the first start of the day or if the truck has sat for a 8 hour work day, oil level is good just recently had oil changed, seems to be running properly and there are no leaks.

Asked by for the 2005 Chevrolet Tahoe
Could be just a bad oil sending unit.
I am going to go get a oil pressure switch this weekend and change , will let you know the out come thanks!
U Bet, let me know.
Sorry, it has been bitter cold here, so just got it switched out tonight and seems to be no change, got anymore ideas as to what it could be???