It is not an issue at all. It happened 3 times with me during the whole winter, and I quickly wiped and cleaned the lens. The windows and mirrors get dirty too, we often clean them.
Is cleaning camera lens for a total of 3 times in a year a big deal? We clean our cars a lot more than that.
City 2013-14 Avg.
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Syracuse 131.6 123.8
Buffalo 128.7 94.7
Rochester 112.3 99.5
Binghamton 84.4 83.4
Albany 71.1 59.1
from: http://goldensnowball.com/