Welcome to the smiley wheel club. You can't get that 'smile' out anyway that I know of, and I've tried a lot of different ways. If you don't have any significant wheel runout (Side to side wobble) then run it. If you do, you can true the wheel and still run it as is. (W/smile)
Like Farmer John said, check spoke tension. About 99% of the time it's just one side of the rim and really doesn't change the spoke tension. (Check anyway though)
Don't let it embarrass you. It's not a sign of you being an unskilled rider, rather a sign that you ride hard. My two cents.