Never would I have thought someone would get upset of a cashier saying no problem. You're welcome and no problem mean the same thing to me. At least they responded at all. Unless there was a major change in tone I wouldn't have even noticed.
Narcissistic Abuse. They actually DO all the things they say they despise in others. Projection, triangulation, splitting, secretive, flirtatious, mean, charming( only if they need you for something), mind fuckers (gas lighting) just avoid at all costs.