2003 Mercedes-Benz E500 Question: A/C vent air not blowing normally

The A/C vents cut its air flow while on a trip from Tucson to San Diego. It was about 100 degrees outside but the engine never heated up above normal. I could hear the fan blowing but it was not coming into the car. The mid-fan setting was barely a breathe of air. The following day it worked fine again on a sort drive. Should I have the dealer check it out before I go back on the second leg of the trip?