Are we talking about frost like what you get after fueling? Or is this "frost" small amounts of ice and snow?
Frost from recent fueling wont be an issue, but if they were sitting there with snow/ice actually on the top of the wings my comment below may be appropriate. However, if its really, really cold most fresh snow will blow off at just a few knots. But if its wet(er) snow, then it may stick.

As a pilot, or flight attendant or knowledgeable passenger, someone should have said something. USair 405 and Air Ontario 1363 crashed for the same reasons. Snow and ice accumulation after incorrect or lack of deicing procedures. A few of the passengers noticed the wing contamination but failed to say anything. One was a captain from another airline but he didnt want to upset the flying crew. Could have saved alot of lives if he nutted up and said something... At least make sure the FA tells the captain there is a safety issue brought up by a passenger.