How rude!

Every so often, i experience something which afterwards leads me to question whether or not it was real.

Today i had such an experience. I answered the phone, and the fellow on the other end asked me for something. He was on a mobile phone, and i couldn't quite grab what it was he asked me, so i ask if he could please say that again, i didn't quite catch it.
"You heard me." he says. "You heard me. You're just trying to act stupid."
Excuse me?
"You heard me."
Sir, you're not on a good signal, i'm having a little trouble hearing you.
"This is a new phone." (as if that ever mattered) "You heard me."

...At which point i hung up.

Now, i may be alone and mistaken for thinking in such a way, but this seemed to be a rather unprovoked outburst on his part. I'm not entirely sure what i did to deserve it. I sometimes wonder if people actually set out to have an argument with a random person, for reasons that seem unfathomable.
Even if i assume that the guy was genuine, i can only wonder what he thought i'd have to gain by pretending not to hear him. If i didn't want to talk to him, i wouldn't have picked up the phone. (Alright, i don't want to talk to most people, but i have to pick up the phone. Nevertheless it'd be a bit pointless to pretend i've gone deaf immediately afterwards).

It's also worth mentioning that not being able to hear something isn't a sign of stupidity in any way. As a matter of fact, a good sign of stupidity is accusing random shopkeepers of deliberately not listening to you, presumably to annoy you.

Again it appears to me that there is a widespread belief that shopkeepers are devious, untrustworthy beasts, dedicated not to making money, but to making your life as difficult as possible, and to prevent you from buying things you need.

Maybe they're right, and i've been doing this wrong. If so, someone please tell me. I want in on the fun.