If you are starting to question the discs then pop the car along to an MOT centre and see if they can squuze you in for a brake test
If the discs are warped in any way then there will be a fluctuation shown on the testing equipment.
Have you had to stop sharply for anything? Cat dog person jump out in front of you making you slam on the brakes?
After driving, does the wheel with more dust on it feel warmer than the other side?