Maintenance just consists of blowing it out with compressed air to remove dust. If you use an actual air compressor dont crank it up to 90psi or at least use something to keep your cooling fan from spinning. This is not necessary but something I learned to do just in case. You could spin the fan up to high with the compressed air and nuke a bearing or the contacts within the motor. But canned air works fine too. You also want to check to make sure that the heatsink isn't loose. You do this by poking the side of it with your finger and if it moves you have a problem
If the copper looks like an old penny where it is just a little brownish then I wouldn't worry about it. However, if its silverish it doesn't sound good. For it to be literally rusting the computer would have to be in a high moisture environment. Like a leaky basement, garage or outside. If your computer is on or next to your desk inside your house then chances are after a year it isn't rust!
If you are worried about it install coretemp to monitor your temps.
http://www.alcpu.com/CoreTemp/