I was doing a series of dungeons last night, and noticed someone used Stone Skin in the Haukke Manor. I was synced to level 29 from 30 so I guess that is the cap of the zone, and I understand Stone Skin is a level 34 skill... this is making me quite confused...

Level Sync wont restrict all powers from being used earlier than they are earned?

If no, is there some rule, like "keeps all skills for up to 5 levels above"? Or are exceptions on a skill to skill basis?