It is not a good idea to touch the mirror with anything other than the correct sort of swabs if blowing it does not get rid of it.. I think this is more to do with the dealer as I think selling cams without a lens can lead to people taking off the protective cap to take a peek... The dealer should take some responsibility for this.. Complain to Canon

Danny O'Byrne  http://www.digitalartzone.co.uk/

"All the technique in the world doesn't compensate for the inability to notice" Eliott Erwitt