Dwarfism or runt??

Hi all new here and I have a few questions. I purchased a male Orange Hypo Leather last Sep(9/30/10). Everything is going ok, He is doing good, eats lots, loves his baths and going out for fresh sun.
When we first got him he was 7 1/4" and six weeks old.
He loves eating his greens, asst. squashes, carrots, crickets, dubia, phoenix worms and an occasional wax worm(2-3 every other week when my birds get them).
He's in a 50 breeder by himself, 75w spot gets basking spot to 112f, 40w household bulb to keep ambient hot side about 89f and cool side about 75f. 24" reptisun 10.0 mounted inside to the top of the screen. Bulbs replaced every 4 months. Cal dusted once daily except on the weekends and he gets his vitamins.
Now I have had dragons since I was about 12 yr old, now 27. I have cared for over a hundred babies and dozens of breeders/collectors. This is the first dragon that I've had that just will not beef up. Seems like he stopped growing around 5 months old. He is about 15" and 140-160g. He eats and poops everyday; veggies at 630am, insects at 730am/1230pm/530pm, bath at 7pm, bask till lights out at 8pm and then cuddle and bed time.
Could he just be this late of a bloomer. He has been to the vet for numerous fecals, all clean.
His cage was on top of a 5ft tall dresser (top of tank over 6ft off ground)and I thought it might be that, so we brought it down to chest level(top of tank about 4ft off ground). This was at the beginning of June. The only thing this has done is cut his wild side/aggression spurts down, but has now started to hiss every once an awhile. He does get the stink eye from my dog now that he is easily visible.

Any help or insight will be greatly appreciated!!

Thanks
Mike