I am 18 and have walked on my tiptoes since I was a toddler. Could something be wrong?

I have no known nerological or physical problems. In fact, I am valedictorian this year of my senior class, and I am considered to be very intelligent. It has never really posed a problem (besides a little teasing) until a teacher told me that her friend's son walks on his tiptoes and he has autism. I noticed that on the toddler page people assured a mother that is was just a phase kids grow out of and that "you never see an adult walking on their tiptoes." Um. yeah. exhibit A.