My status with the NCR is LIKED.
I was working on some side quests when out of nowhere an NCR MP approaches me and says "I cant believe you are away from the strip.No one f**** with the NCR and lives" and proceeds to attack me and anyone around attacks me too.
I reloaded the game and tried several different quests and he still showed up.So I spawned in an isolated area and when he approached me again I killed him.
I'm very confused why this happened.

Are you wearing NCR armor?

I think this is a triggered event related to the quest involving the Kings and the NCR. I was also confused, but it sort of makes sense given the quest.

no I have t-45d power armor

Looks like the game skipped some steps. If you have a bad rep on the strip, the MPs are meant to shake you down for caps. You should only get attacked if you refuse to pay, I think.

Probably the game started the guy approaching you on the strip some time but you out-ran him and the "quest" skipped ahead.