Xbox 360 tray problem?

It's a known problem with certain machines. Mine does it, too. If your 360 is standing vertically, try laying it down - this fixes the weak motor problem in most cases. Microsoft should pull it in for repair if you want to take that route, as the hardware guarantee for repairs is now 3 years. Really, it depends on whether you want to be without your 360 for a while or not, it's not a critical error.