From 1908-11, there was no 'h' at the end of Pittsburg.
Not trying to out the auction - if I felt it was legit to 1909-10 I would be bidding very reasonably, so no one would be getting this cheap. But that 'h' at the end has be concerned...if only the moths had nibbled it off.
http://www.ebay.com/itm/251216132173