Maybe the OP has just started to have a hearing problem.
I have had for several years a very bad hearing problem with my right ear. My speaker levels are kept close one another, but when I listen to music at 11 feet from the front speakers, the sound seems to be louder from the right. I guess my brain is attempting to compensate for my bad right ear. However, if I get closer to the front speakers, the stereo balance improves.