Can a Warning Turn into a citation?

So a couple days ago I was pulled over (NJ)- presumably for speeding as the officer said but he didn’t state how far over the speed limit i was going. the whole encounter was pretty strange. but to keep it short and sweet I believe I was given a verbal warning as he handed me my information and said “slow down for me”. I wasn’t given any paperwork from the officer. is it likely to receive a citation in the mail afterwards? or is it like once the stop is done it’s over?