Help! Blue Jaw Trigger acting weird? Injury?

[Rskillz]

Hey guys, just got a small Blue Jaw Trigger who was doing great after dripping, happy as can be, and then all the sudden he is lying on his side on a plateau of rocks, and it almost looks like he has a cut or slit by his dorsal fin or he was injured. I have no other aggressive tank mates...What the heck?

The LFS said they would get me another if he died, but I really liked this guy =(

What to do?

[Rskillz]

Or is this slit where they tuck their dorsal?

[whorulz1147]

I think some triggers sleep on their side and people often become concerned the first time they see it. How is he doing now?