3 & 4 yo's are impulsive and irrational. It's rare for them to be able to explain why they do things ... they just do them.
If childcare are saying he definitely needs to see a Paed then do it, but if they aren't I wouldn't rush at this point. I'd read a book such as Raising Boys and get some strategies for disciplining and managing 4yo behaviour. If he's still struggling in 6 - 12 months then I'd think about a referral. But to me, he sounds very normal.