my son will complete 4yrs next week. he is the only child. whenever he plays at home...he is talking to another 'imaginative' child and having a good talkative conversation. do i need to be concerned?

haha.. I used to have imaginary friends myself. I am the youngest in the family and have big age gaps from my sister and brother. They are at school and I'm alone most of the time. Thinking back, I would say that I am fully aware that they are part of my imagination (I do not "see" them as any "physical" form and just imagined their characters/personalities). I grew out of it but they will always remain as part of my childhood (they are my playmates!). haha.. I would like to think that I turn out normal (and fine!). So, don't be too worried. :)