Are you sure? Like, did you try blowing on the cart and shit (or something) to see if the data comes back? The advance carts are usually pretty shitty with SRAM like that sometimes, so it's not all too uncommon for them to shit out every so often.
But hey, you submitted your scores already, right? If not, then there might be a problem. :P
(And there's always Gameshark to get your progress back =P)