Why are you arguing?

Yesterday after schoolwork was done, I sent Bradley to clean his room. A little while later Calvin and Bradley come into the kitchen in the middle of an argument. I'm not paying close attention but it sounds like they are arguing about cleaning their room. After a few minutes it becomes semi-clear what they're arguing about. I think Calvin went in and offered to help clean the room and Bradley got mad and told him he had to help clean the room. (Pause for effect). Yes, they were arguing the same point to each other. I figured I'd let them work it out themselves. After about five minutes I got sick of listening to them and said, "That's enough, both of you go clean your room and work together!" (I may have yelled it). I'm not sure which one of them, but one said "Finally!" Which was quickly followed by "Thank you, Mom, " from both of them. It was like they were just waiting for me to solve their non-problem for them. Weird.