Had a strange experience today. I used a HH purse that has outside pockets that close with magnets, I used BART (rapid transit in SF) today and put my cards in the pocket. When I tried to use the ticket at the end of the trip it was de-magnetized. I had a second ticket with me and when I tried to use that for my return trip, it too had been de-magnetized. I have other purses with magnetic closures and have never had this problem before.