I am at McDonalds daily (ya ya I've already heard it) (my life my choice) and would say I drop at a minimum 1000 bills there per year and have never had a comment about my markings. Was it some 16 year old that thinks they are a Money expert? My five fly through their tills so fast the staff probably seldom notices the stamp. I am surprised I have not received any of my own bills back. As a person who spends a few fives I must say I seldom am confronted about my stamp(S). And trust me my stamp is large round and hard not to notice. Maybe Saskatoon is too use to seeing the stamp.