Thanks for everybody's response. I guess I should feel guilty by saying "I am pleased to know I am not alone",

. But seriously I am surprised to see this is such a common problem in Canon's high end and highest end offering.
A couple of you mentioned sending to Canon for service is an option. Where would I send it to ( I am in southest US)? Sorry for the newbie question but photography is my long time passion but recently getting serious hobby. Also should the cleaning be free as it is entirely due to their poor QC?
Jack - thanks for your valuable suggestion, but there seems too much risk to clean it by mysefl at this point, as right now it is just a nuance and does not affect pictures.
I should also say that despite this unexpected "feature" (per Neuro), the camera is really working like a charm! Used it for a Sea World trip and almost all pictures were worth to keep and there are thousands of them. And that is another "problem" I am having with this camera,

.