ouch.. pity. sorry to hear.

Maybe it finished exactly 90 days after, i.e at whatever time you started it, instead of midnight?
or is it Server midnight or something?

i remember reading a post (from Vyndree iirc) about her losing a day or half a day with the same granting issue. And the blizz tech support guy had it wrong or something.
If you do a forum search you might find it.