2008 Nissan Altima Jerky Movements

On two different occassions, during rainy weather, my car has jerked several times. I was driving at a very slow speeds on the Interstate (freeway) both times this occurred. I am going in to the Nissan dealership on Tuesday to get a 100-point inspection. Could this be considered intermittent misfiring and if so, can it be diagnosed from the inspection? Another question, if this is in fact misfiring, is this a terribly expensive problem to correct?

Thanks so much

K Williams