Shorter canter stride?

I have a 15.1-15.2 quarter horse paint. I know that a normal horse stride is about 12'. I set up three canter poles and kept moving them closer until my horse was cantering over them cleanly. The poles were about 9.5' apart and he was moving at a fast hunter pace. Should I be concerned about this or try to change this. If I should try to fix it, how would I do it?