My DS is 4, nearly 5, and I have found how he plays a bit odd for a while.
He loves toys - generally anything vehicle related including Transformers, Octonaut Gups etc. His main method of play is to push his vehicles etc around or make them fly, whilst making the relevant sound effect or singing/humming a little tune - sometimes the TV theme tune of whatever toy he is playing with. He doesn't seem to do very much narrating at all.
His imagination seems fine, not hugely creative, but spontaneous enough. He is fairly needy and always wants someone to play with him, and when I play with him there will be a very basic plot line.
I see other boys his age playing out elaborate storylines on their own with toys or in the park etc, and DS would just never do that, or if he would it's extremely rare.
Does this sound normal/familiar?