Priapus Died in the Parking Lot

I still say that if you ask them to pull codes, you are requesting specific work, and if they want to be unfriendly they may try to charge you for "unneeded" work if there are no codes.

But if you go in and report the problem and ask them to investigate, then you are well within your rights under the warranty, and they cannot charge you. And the obvious, first thing for them to do is to pull the codes. And when they tell you there's nothing wrong, you can ask them if they pulled the codes. And if they say no, then they're incompetent.

REPORT THE PROBLEM, AND ASK THEM TO FIGURE IT OUT. Let them decide that pulling the codes is the obvious first step, and they cannot charge you for bringing the car in after the warning lights flashed, telling you to bring the car in!!!