I'm sure there was a reason, I trust Zack0 and believe that you have done something stupid that you aren't aware of. This could include, asking loads of stupid questions on the server (can I beta test, where to download, can I have admin, how do you _____) or getting in the way of what he is doing, pressing events, or building random things when its not a build server.
Just some ideas, I'm not saying you necessarily did any of the above, but I find it more likely than Zack0 banned you for no reason at all.