My son (now 7) had a lot of issues in preschool. I wish I would have had your insight at the time. I just thought he was acting up because we had adopted two chrystal-meth kids who needed a lot of extra attention at the time.
I remember his teacher telling me that she was no longer going to send him to the office, because he would charm the principal and come back to class with a sticker. She also said the principal thought she was crazy (always complaining about my son's behavior). For the rest of the year, she basically ignored him. He learned absolutely nothing.
Once he started Kindergarten, it was obvious that something was off because he mastered the curriculum in about a week, and then the real behavioral problems started. We are now homeschooling and he is doing GREAT.
You are doing the right thing investigating your son's issues. I believe it is never too early to start nuturing the special needs of a gifted child. I feel like my son would have been spared a lot of pain if I had been a little quicker to figure out what was wrong during preschool.
Good luck to you and your family.