Romeo Leblanc Stamp - Possible Variety

I have two panes of 16 stamps on The Right Honorable Romeo Leblanc, issued February 8, 2010. On both pane I have noticed a yellow mark in front of his chin. The mark is identical and located at the same place on stamp no. 5, on both panes.

I also checked with a friend who has an identical mark on his pane.

I don't know if this a constant variety. However I would like to know if somebody else has the same mark.

On a different note, I am not familiar with stamp scanning. It took me a lot of trials and errors to end up with the above picture. Hopefully it is clear enough. If not, I would be appreciated if someone could run me through the steps for making good scan pictures, and show me how to add arrows where necessary.

Any feedback would be appreciated.