the edit thing still needs some tuning as evident on my above post, I will post it again..................makes sense, the prop. valve allows the rears to come on before the fronts, with the rod too long its not allowing the brakes to release completeley, adjust some freeplay into the rod as you might with a clutch, but maybe a 1/8" or so.

I've replaced the masters on quite a few Sharks over the years, and I have seen some that the piston in the master, where the pushrod fits, is NOT the same depth, or shape, as the one I took off. Sometimes it simply requires a change of the length of the pushrod(adjustment)....sometimes ya just have to get the correct master. I would definitely be leaning towards a small adjustment in this case, IF the dragging when hot is the ONLY issue with the brakes.