I notice asymmetrical postures or movements because I have a similar problem. I believe it stems from years of a painful back problem, which is no longer much of a problem, but seems to have caused permanent list. I also have a knee that tends to flop to the inside and brushes the top tube. I mostly corrected this with a shim under the right cleat and padding under the arch to push the knee to the outside.

There may be an old injury that caused some muscle memory like the dog who injured a leg requiring walking on three legs for a while but still walks that way long after the injury has healed.