I'm just going back from Seoul and didn't like someone shutting me up in the bus.

I was riding the bus from Seoul to Incheon and was talking to a nice Korean lady who has lived in Chicago for the last 20 years or so when, out of the blue, the lady in the back seat from us starts talking madly in Korean to the lady besides me, after this, the lady besides me tells me we should stop talking because we are bothering her and can't work. If that would happen in the US I would have just said fuck off. Is it not acceptable to talk in public places in Korea?