The temperature spread of 6C between all cores under load is not bad nor radical. Your temps are in the "safe range" with 40C headroom but I would expect to see mid/low 50's with that processor at 3.7GHz.
If you are concerned that you may have not seated the HSF properly (or misapplied the thermal compound) go ahead, remove it and compare the HSF base and CPU to some of the online "thermal compound spread" pictures to see if your application technique is sound, reapply your thermal compound (it actually gets easier with practice) and try again.