Crazy Train

I need your advice. I was mean to a complete stranger today. Here's what happened.

The train was short today, so everyone was packed in like sardines. At Seaford, a woman with a cell phone to her ear walks up and sits in the bench catycorner from me. I recognize her as a repeat offender. She's talking loud, and I could barely hear what I was listening to on my mp3 player. After several minutes of waiting for a break in her conversation:

G-Man: Could you please finish your conversation and hang up?
Lady, obnoxiously: No.
G-Man: Please.
Lady, very nasty and annoyed: No.
G-Man: Can you see the sign above my head? It indicates no radios.
Lady: It's not a radio, it's a cell phone.
G-Man: It's a radiotelephone. Please turn it off.
Lady: It's a cell phone. NO.

Now I'm pissed.

G-Man: How do you think the signal gets from your phone to the other one, idiot?
Lady: I'm not an idiot, it's a cell phone. Why don't you turn off your radio?
G-Man: Oh, I'm sorry. I can't hear what I was listening to with all your blabbering, but if its really bothering you, I'll just turn it off and listen to your half of your conversation.
Lady, on her cell phone: Hold on, i got another call (hits flashook, ignores me).

I felt bad. 5 minutes after she hangs up, her phone rings again, and she answers it, but sulks talking quietly in the corner.

My question is, should I have said I was sorry for calling her an idiot?