If most of the country is like the Gainesville market it's the local stations that set the
PSIP "clock". Now why this "clock" is not tied to WWV or even the network I don't know. I don't know that much detail of the inside of the new digital studios. But apparently they are not kept on time automatically.
Here are my current local stations by network
WUFT PBS 0
WJCT PBS 0
WTLV NBC +31 minutes
WJXX no reception
WCJB ABC 0
WGFL CBS -1 minute
WOGX FOX + 127 minutes
All of them had the correct program data to match their time.
Except WOGX, which said it was 8 pm something and the program guide had the 11pm news. Now that is messed up!
Also in the above list WGFL doesn't normally run that close, they are often an hour off.