We are all born with asymmetry of some kind. Some are more obvious than others. Sometimes the muscles and nerves that control facial movements are weaker than the other side, causing the appearance of a smaller eye, crooked smile..etc. Sometimes dental freezing can cause this type of permanent damage as nerves can be permanently affected. Unless this problem occured overnight, I would say it is perfectly normal and you have nothing to worry about.
i have the same problem. kind of. the lid on my right eye is lower, which gives the appearance that my eye is smaller. i usually sleep on tht side,so it could have more wrinkles. make sense?