Automatic Litterbox Central

First, I love my Littermaid. The cat thinks it's pretty swell too.

Tonight was the night to clean it out; upon plugging it back in I was a bit lazy and left the power unit plugged into the wall, and plugged the small round end into the Littermaid. Ooo, got a little bit of sparkage there. If you wiggle the power cord around a little, I can get some sparks produced, but once it's plugged in and left alone it's fine.

Anyone else seen this issue?