Actually, that's common with a lot of lefties I know. Psychologists like to think the right handedness is simply a way of immitating others, or possible, it's simply their conditioning. After a while, the conditioning wears off and the prominent side of the brain starts to take control. Furthermore, it's not that you became LESS proficient with your right, it's that your left excelled far faster than your right. You probably didn't lose anything, it just didn't continue developing connections in your brain as frequently as the left.
That's all I remember from Psychology class, so don't quote me. I can't be arsed to look it up, either.
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