In April I bought a 3-Day Park Hopper for $148 and some change from LMT (Last Minute Travel, for those who aren't sure what that stands for) and upgraded to a Deluxe AP the morning of the 3rd day. I was expecting to pay $151-ish, which would be the price difference from what I paid for the hopper and the cost of the AP. Instead I was charged $115, which would be the price difference if I had bought the hopper online for $184. Anyway, I mentioned to the Cast Member that I had bought the ticket at a discount, told her how much I paid, etc. and that I was prepared to pay the full difference. She thanked me for my honesty and said this was fine, so I just paid the $115 -- bringing my AP to a total of $263. I'm not sure if this is normal or not, though.