I think you are maybe worrying that one of the children seemed to be bullying the other, and you are feeling bad that you didn't do something to stop it.
I don't think you need to feed bad.
I don't think it was bullying. I think it was just kids getting over-excited and expressing their feelings too loudly.
Trying to prevent bullying is always a good thing, but don't be too sensitive about it. Kids don't always speak to each other in polite language - they yell at each other and are rude to each other, but unless it is focused and sustained and upsets another child, I don't think you need to worry.