Mutation or Disease?

Ive got 3 plants growing right now, about 5 weeks into flowering.
The 2 of them are coming along beautifuly, but the one is a little um "special"

The very top where it is usually supposed to be filled with hairs and buds ect is not.
No hairs at all and just looking like leaves.
The leaves are very messed up, they feel about twice as thick as normal and are very mishapen (twisted curling to one side ect), the color is spot on dark green but they just dont look right if you know what I mean.
The tips arent burned either.
The rest of the plant looks awsome, plenty of furry bud sites.

I havn't treated this one any differently than the others, same watering shedule, same nutes ect.

Random bagseed
Soil grow - ProMix DX or something like that
400w HPS
15-30-15 nutes once or twice a week depending.
12/12

I will try to snap some pics when my car gets out of the shop, camera cord is in there

Pic as promised
Those leaves are very rough too, almost like sandpaper.
This is the very top of the plant where it should look like the bottom pic.



Here is the other plant, planted at the same time same nutes same lights same everything.


I know its a lil burned, got too close to the lights heh woops.

looks like it got too close to the light n melted

damn that thing is a freak.