I've read through the M1355 bulletin a couple times now, and no where does it say to just inspect and return to customer. The way the bulletin is written indicates that all bikes in the suspect group should get a new master cylinder kit. Inspection of the release plate is the other part of the bulletin, and if the wrong plate was installed there are instructions to replace the plate, pushrod, actuator O-ring, etc.
I would seriously question any shop that tells you they just did an inspection and didn't need to do anything else. Perhaps Harley has refined the suspect bikes list based on build date and the bike is no longer considered suspect. But it could also be a case of the shop not understanding the program. It definitely wouldn't be the first time a Harley shop didn't know what they were doing.
Jerry