Retention Settings arent actually the final thing that someone should go by.
The last step in Mounting bindings or adjusting them to certain boots is called an A.S.T.M. test. You use an arm-like mechanism and pull and twist your boot out of the bindings, this will give you a reading in how many Newton meters of force are being applied to the boot for the binding to release. On the same chart, there is a range of NM that it should fall in. This will test the amount of Forward pressure on the heal, AND the twisting on the boot in the binding, if you're not in that range... there are situations where you can adjust the retention settings on the binding to fall in that range.
So it's very possible that the shop guy didn't screw up, he was just doing is job very well. Your binging could have been releasing low on the twist or heel tests and he had to turn it up.