I just had my tires rotated yesterday and then my flex unit and sway bar replaced today. they did not see any problems with the car when they were looking over it other than those and they are now fixed but ever since my tires were rotated my back tires seem to be making a slight woo-woo-woo sound (if that makes sense) it's not driving bad and it does not feel off, but I'm not sure what this is, it stops when I'm stopped. The car is a 98 mystique with 52,000 miles on it. What could this be? I'm driving back home from school in less than two weeks and have little to no time to have my car looked at again since they have seen it twice in the last 24 hours, and today they did not say anything about anything else being broken.
oh i forgot to mention the drive home is about 15 hours/800 miles. my dad will be with me and i have triple a coverage.