Need to know some more info. There is indeed a possibility it could've worked that fast but it would be unusual. It sounds like you didn't use a starter and only smacked the pack which would also be strange for a quick ferment.
What was the OG?
What is the current SG?
You sure the temp was only 62? A higher temp such as 70+ could possibly result in a real quick ferment.
I use Pacman quite regularly, and the typical ferment is about 3-4 days but I have had ones that finish in closer to 2, particularly lighter gravity ones. My ferm temps are usually between 60-65.