User blog comment:PRICEY PEARL/SAM'S SLEEPY YEAR........ A SPELL?/@comment-4544974-20121101224835

No, I doubt Sam's year off was due to some outside, supernatural force. Sam never wanted to be a hunter; Dean said it himself in 4x22:

"Sam never wanted part of this family. He hated this life. Ran away to Stanford the first chance he got."

Tbh, I think his feelings towards hunting haven't changed one bit.