Have a Silver Satin mini blem that's three years old. The blem didn't show up until about a year ago - the logo wore off (it's a 2.0 which has a stenciled logo instead of the 2.5 etched one). Uh oh! She's nekkid!
When I first got it I looked and looked for a blemish, but I couldn't find anything, except that part of the logo seemed a little faded. I forgot about it until one day I noticed the logo had disappeared.