Why is there this difference in crew attitudes?

Flew from DXB to MSP last week. First leg was DXB - AMS via KLM. Very nice crew. Polite and always smiling.

Second leg from AMS - MSP was via Delta. The crew seemed agitated before we even boarded the plane. One of em as serious as a drill sergeant. Another frustrated FA called us passengers grasshoppers (a mom with her infant moved seats last minute cuz she was waiting on another passenger to move) xD

The MSP crew is usually nice. I flew with them twice before this and they were good. This crew, if I caught it right, was from NY but flying from AMS - MSP (idk if it works that way). Why is the NY crew so frustrated? What have you New Yorkers done to them?! Lol