From what I know, CDP bonus is invariably counted towards GMT = UTC, official tournaments like weeklies and monthlies invariably begin and end in San Francisco time = PST (UTC+8) (oops, UTC-8) or PDT in Summer.
Some have seen a change in the time stamp of score history entries. IMHO they have been in Pacific time, too, but now they are in GMT. Proof has been found that it has been like today since August 2013 at least.
Concerning the time before, there are different opinions. Some say, it has been like today from day one, some say, there has been a change at some time between Aug 2012 and Aug 2013. No proof given yet. I see a good hint in the fact that I found no deviation in my early 2012 scores when I played frequently and more.
Additional proof may be found in your score histories including CTTH entries, Monthlies or Weeklies before August, or in privately saved scores. Montlies are easy to spot, see this example:
09.01.13 August Bali Hai Sweeps Master 278.9
09.01.13 August Oakmont's 9-hole Unlimited Tournament Front 9 Master 34
(August tournies played in Sepember?)
and here is a fantastic example of Weeklies:
08.05.13 Wk 32 Closest-to-the-hole Challenge Legend 188.65
08.05.13 Wk 31 9-hole Unlimited Play Front 9 Legend 33
Impossible to play two different weeks on one day unless time zones help...
You may spot others by expanding the date to show the day's name.
Edit: The other relevant thread is Days played in Bug Logs.
Edit2: @dacrash: The new date shown is not the reason for a missed CDP but only the proof that the game ended too late, after midnight GMT. Your bad, I'm afraid.