Odd, when I do that, it says $51,99, ah I see what you mean.. in the next screen.
Well.. look at the price next to it.. that's still 51,99 like the price in the main screen.
Might be a bug in the system to be honest, don't cheer just yet.
Cause when you then change it back to euro's the price stays 40.
and it can't be 40 in both currencies.. and 40 euros = 52 dollars..
I'll advice you to not take that 40 dollars to be the real price, I think the system is flawed there.