Hello! I was traveling back to my college today and out of no where my car starts vibrating and making a funny noise on my left driver's side... it did this on and off for about twenty minutes. I know nothing was wrong with my car because I had taken my car in to get fully looked over days earlier... my mom called the place where I always go for my car services and one of the workers said that it couldn't possibly be anything wrong and that the only thing could be is that ice must have frozen on my rim(?? )(<--- if that is the problem, should I worry? What would I do to fix it?) however, I got back to school safely without any vibration or noise. Weird!! Please help!!

A clump of snow, ice, or mud stuck to any part of your tire will cause this. If it only occurs above certain speeds all the time you have a tire balance or linkage problem. It sounds like the problem is as your service person described.