Try this. Might work, might not, but worked for me after my clock app exhibited same or similar issues after Gingerbread update.
Go to phone "Settings," select "Date &Time," deselect "Automatic" checkbox (i.e., turns off time server sync).
Now go check and see if everything back to normal re clock. Whether it is or not, now go reselect the "Automatic" checkbox to turn time server sync back on. If your clock app went back to normal after deselecting "Automatic," it should retain after reselecting it again.
If the above works for you, then you may need to use this process again in future as it appears the clock issues also can happen as a result of installing / uninstalling apps.