Too short don't take a chance running in big big combo is actually ok for most drive trains as long as you do not spend a lot of time. Add at two links links back on and a little cassette wobble is ok but I would simple go back make sure you have the 1mm spacer for a shimano 10 spd drive in the rear. Then tighten down the cassette per torque specs which is actually fairly tight. It does not need to be super tight but not just snug up either.