anti-social behavior

Our only child is almost 5, has attended daycare/pre-school since 1 year old and converses and plays well with the friends he knows.  When  he first arrives, though, he likes to be alone and quiet and even covers his ears or shuns friends who greet him or want to give a hug.  I fear he will alienate himself from them, though it seems he does play happily withe them later in the day.  

He also goes out of his way to avoids 2 adults.  One was his teacher when he was 2.  He liked her when she was his teacher, but now if she waves or tries to talk to him, he rejects her because she is overly enthusiastic in his opinion.  She is from Eastern Europe, so her accent may be part of it?  He also seems to be sensitive to people's smell.

The 2nd adult is a city bus driver.  We used to take a city bus to daycare and one driver made a point of saying hello and asking casually friendly questions (it is a small town and many riders on the bus route know each other or the driver, so he was not doing anything improper, my son just didn't like that he was friendly.  Later he also said there was a bad smell when we rode his route one time.  He will not ride that route anymore.

What do you make of this?  He is an introvert but gets along well with friends and neighbors he knows well.  he often asks to have one of them come over to play.  He has a good sense of humor. He likes detail.  He is very attatched to Mom (wanted to breast feed for a long time, would like to be snuggled until he falls asleep, likes to have Mom play with him but also enjoys helping/playing with Daddy and going places with both.

[jdtm]

These are signs of anxiety; probably not of an anxiety disorder.  There is lots of information on the internet - try googling the term "childhood anxiety" or something similar to better educate yourself about this issue.  I don't think there is any reason to be overly concerned; often children with some anxiety display traits of sensitivity, compassion and empathy - not a bad thing.  One book you might like to read is "the highly sensitive child" by Elaine N. Aron which can be found on the internet, bookstore or perhaps in your local library.  I wish you the best ...