No, that's not it. If that was the case I would have opened it and pulled out the plastic tab. It's the actual chip itself that shakes just a tiny bit.
Why wouldn't it? You asked in my other auction if items are in smoking environment. I do smoke cigarettes in my work room, so the short time that I possess things, they are exposed to smoke. Are your kids asthmatic?
Ah okay I see what the issue is here. The circuit board doesn't fit snugly inside the cartridge and so there's some play in there. That's pretty normal and not a concern. No loose rom chips people XD