if you noticed, it wasn't even that. I pasted the exact situation as it happened.

We maintain Guest*!*@* as a banned mask, and have our general utility bot Naruto-kun enforce those bans by kicking people with matching hostmasks. So when your nick goes to "Guest198675" or something like that in the channel, Naruto-kun kicks you. You can come back in the moment your nick isn't Guest*. This works out well, keeps people with nick protection scripts from flooding the channel with their nickchanges when services hiccup, and generally makes our lives easier.

Pay attention Albino! :-p

On a side note, our bans expire in one of three ways:
(1) scripted bans (those triggered by certain channel text) are scripted with expire times. The banner auto-unbans the person after a certain set amount of time, usually a couple minutes to a couple hours.
(2) someone is bored and decides to clear stale bans.
(3) services crash, a server splits, or something else happens that causes the banlist to be flushed.

Sometimes the op who banned you will unban you. Most of the time our bans don't last longer than a couple hours, though sometimes they've been known to last days or weeks (and there are some people that we ban forever, because they're cockmonkeys). Don't be one of them.