We've worried about this with P too. She always seems to be falling and bumping her head. Short answer, I don't know. I guess you know your kid though - if they act out of character after a head-bang then it's worth checking out IMO.
We've an extra worry because P's pupils are uneven, pretty much all the time. She is an oddball. So that symptom isn't a diagnostic one for us!
GL - I hope she's more coordinated soon