The yellow dot is an indication by the manufacturer that this is the lightest spot of the tire and should be matched up with the valve stem which is usually the heaviest part of the rim. This allows for less weights to be added to get a balanced wheel. The red is usually a high spot on the tire. Tires are not 100% round so there is always going to be some variance with them. Again the red dot should be installed over the valve stem unless you're using steel rims, then there is usually a dimple to mark the "low" spot on the steel rim. When you have both yellow and red dots, the rule is that "red rules" and use that one for mounting. Here's a good article that explains it all:
http://www.tirebusiness.com/article/20070813/ISSUE/308139967/are-you-seeing-dots-those-color-coded-sidewall-markings-serve-a
I wouldn't worry to much about it. As long as a reputable shop installed the tires and balanced them and you are not having any vibration issues I would just leave it be.