Jagex is a little over-sensitive about those things... are you sure you were banned because of that particular phrase, did you ask Jagex to tell you exactly what you did?
Anyways, I have a story:
Once upon a time, in a bank not far from the Mage Guild, lay a friend, a player mod and a noob. The noob reported the player mod for Jagex Staff Impersonation, because he had a crown and said he had the ability to mute people. The noob then ran away. The friend sarcastically said "Omg!! You have a crown!! Hax!!"
Three days later he was banned. He asked for the reason and Jagex sent him that exact phrase. "Omg. You have a crown. Hax."
The End
Anyways, I hope you get your account back, good luck with that, keep ban appealing.
