Random restart macbook help

Hello,

My 7-month old Macbook has randomly restarted three times in the last two days. Any ideas what the cause is? Should I take into a Genius Bar?

For information:
It has updated with Apple updates about three times in the last 4 or 5 days.
It was not doing anything strenuous when it restarted (it was playing music two of the times and I was in another room).
All times it happened I had only left it alone for ten mins max. I checked the energy settings and these were fine.
I recently turned on FileVault.

I'm not sure if any of that stuff is linked to it, but I thought I'd give you guys the most recent activity.

Any help would be greatly appreciated.
Lou