Divine Shield bugged?

As the title says, is Divine Shield bugged? from my understanding the only thing in TBC that can remove DS is Mass Dispel (which Priests havent learnt yet).

But several times now I have noticed it breaking early, both in PvP and PvE.

I was just doing a Scarlet Monastary (want the Tabard) and on the way out used DS and it got almost instantly broke, from the looks of the log by Shield Bash.