I have the complete apex kit in my shield 40 and the trigger doesn't feel that light. You may want to talk to the shop and make sure the gun you held had the full kit. If you change just the sear and not the springs you will have 4 3.5lb pull. If you drop in a glock trigger spring it actually will drop it down to around 3.15lbs.
Now with the full apex kit including springs installed you should be around 5 5.5lbs. Which is suppose to be 1lbs less the a full stock shield. Unless you have the MA compliant shield. It's about 8 8.5lbs.