The way it looked like it was hidden made me think it was a deliberate attempt to create a lag machine. So you got banned for it, it was a tempban but due to bukkit sillyness its not possible to include a ban reason with a tempban. So you got banned with a message to appeal. I'm not saying players shouldn't make redstone stuff, just be careful to not leave redstone clocks running when you are not playing
redstone clocks like that can and do add to the server lag, depending on how they are made, your little machine probably only used like 0.5tps (ticks per second) however it adds up and you got punished. Redstone calculations are handled on the main server thread, so any heavy stuff eats into the tps of the server which effects everyone. As I run kraftzone with a nice high view distance and a lot of plguins it means the server has to do more work per player! The server can be at 20tps when there is more than 25 players on the server in total and probably a lot more as I have seen it, however with redstone clocks and other redstone related stuff running, that has been known to remove upto a few ticks off the server total tps. When you get under 15tps on a server it can start to become to noticeable lag delay in block creating/destroying and pvp. Now I'd rather run a lag free server with more players on not complaining about lag, and that means keeping redstone clocks made for 1 player to use down to a minimum.
-run your heavy redstone stuff and clocks during the quieter hours while you are on the server and in the area of such redstone contraptions.
-turn off clocks when you finish playing
-and turn off the redstone clocks when the player count is more than 25+ as 1 redstone clock probably uses more server tps in calculations than 10 actual players on the server.
If everyone sticks to these rule there would be a much smoother server when there is many people online.
So those are my rules on redstone, if I have to find redstone clocks when the server is busy and it was adding to server tps lag it will be removed.