Wires crossed

I went via a nearby convenience store on my way to the bus early yesterday morning to buy one of those ten-trip-saver cards that can be used on buses and ferries. The regular behind the counter is an extremely quiet Asian woman. I think her English is relatively limited.

I buy the adult version because my student card expired late last year, and drivers do occasionally ask to see concession cards if you have a concession ticket. Anyway...

I said
"Can I have a concession, two-zone ten-trip saver, thanks?"

She proceeded to get one, scanned it, handed it to me and told me it was $10.80c. I realised when I heard the price that I'd accidentally asked for a concession, not an adult. It was early and I wasn't fully awake.

I poked a look of frustration (with myself), and said
"Did I say concession? I meant adult. Sorry."

I then received a horrified look, before she responded
"but you said concession."

Thinking at the time that she was stating the obvious back to me, I just looked at her and she looked back. A couple of seconds later, she scanned the card again before fetching an adult version. I paid for it and left.

I have concluded that she misinterpreted and/or misheard me as
Did I say concession? I said adult.

And she must have seen the frustrated look on my face as being directed towards her.

Her upset expression made me feel quite bad afterwards.