my left leg might be slightly longer, my left foot is DEFINITELY bigger, but doubt that's it. i've had all kinds of injuries in the past from playing basketball and such. I also have some issues in my sacral spine (genetic) that have bugged me off and on since I was a teenager. In the end though, I think it's just all of the years of sports, injuries, compensation, and lack of mobility/flexibility training.
It's the same story with me, just that it is my left side. Left hip, SI joint and shoulder are often pretty stiff eventhough I do SMFR/mobility daily. My explanation is that I had two very severe ankle sprains a few years back from playing volleyball... one time I even tore two ligaments in my ankle. Since then my ankle has never really felt the same and eventhough I don't experience any pain it just feels odd. It's hard for me to get adequate ROM so I probably wouldn't be able to do front squats with good form without my romaleos. It seems that there are injuries that cannot be undone and you have to try your best to work around them. If that means avoiding certain exercises/activities, so be it. Sometimes you have to be smart instead of fighting through it. Better be save than sorry.