Just noticed this thread, but FWIW:

Rollerblade wheels don't like getting wet. I've always found that as soon as I get mine wet the bearings start to go and I don't see that this would be any different than luggage. It could just be that your bearings got water in them and this is causing the diminished performance.

Now, of course, inline wheels on skates take a lot more punishment than inline wheels on a bag, but it's the same process. Water = trouble. Or at least it is every time I end up getting them wet.