I've been in the Swiss person's shoes myself, actually, and have asked people with overly loud music coming out of their headphones to turn it down. Then again, I've also told kids playing their music on speaker on their cellphone to turn it off if they're being quite obnoxious about it. In that case, it's pretty obvious that what's being done is annoying, but in the case of people wearing headphones, I assume that they typically don't know they can be heard.

Was she genuinely angry with you, or was she so uncomfortable with having to approach you that she just turned red and looked angry? I've seen that around here once or twice... ;-)