I guess I am used to getting an update once a day. On occasion it does seem about once every other month I will see a whole day go by without an update. On those days when I would run an update check I would get the "your programs are up to date" box.
The closest to this current situation that I can recall was maybe back in September 2009 when I ran an update check and the icon was downloading for several minutes before ceasing without installing. That was the first time I ever went on the Community forum and I saw that another user had started a thread stating that he had encountered the same thing. Someone else had written back stating that they too had the problem and that McAfee must have put out a bad DAT file. However in that case when I tried an update check 3 or 4 hours later there was no download just the "programs up to date" box. I figured then that they must have pulled the bad DAT file. The afternoon of the next day a new DAT file downloaded.
So I will continue to keep my fingers crossed on the within 6 hours deal.