I got the exact same problem as u.. Got one obvious stubborn black spot on my sensor showing in my pic.. Try hand blowing it, but no matter how hard I blow, its still there.. Seems to me like a smear, but how can it be possible when I never touch the sensor b4..?
I guess I have to send in for cleaning this week too.. Any1 knows whether cleaning of sensor is covered by warranty and if not, how much will it costs and how long it takes? Thanks..