Just an idea but was it very dusty when you used the washers? If so, dust could have collected on the water droplets, and when they evaporated, it could have left the spots you see now. It just like the water spots you can get on a car after washing it if you don't dry it right away.
Hatch Nation #13 : Rally Revolution #13 : ROTM Jan '13
It's Bryan, not Brian
RSVT-170 Build in Progress
Derusting Rusty Build in Progress