Can you tell if it is going to get worse? Or shall I just rub it as a one off and move on?
It depends.
Sometimes we all lose it and do something wrong. I have, I think that if we are honest we all have. If you can honestly say that in 10 years you have never ever been through something like this before then yes, it could a moment of losing it, followed by "oh fuck, what the hell have I just done?!"
However, if there have been times over the last year or so (you have a baby, how old?) where the arguments have gradually got worse then that isnt good. Abuse often starts during pregnancy and then gets worse.
However, having a baby is a stressful time and I will admit to dumping each of my (6) kids in their cots at one time or another and leaving them to scream because I was scared I would hurt them if I didnt, most mothers have.
Have you ever felt a power imbalance? Are there money issues where one of you has more than the other and there is resentment? Have there ever been times where you have felt controlled about what you do, who you see, where you go, what you buy, what you wear?