Do You Speak American?

I was at the local Co-Op buying ingredients for this peach cobbler recipe I am trying out tonight; while (or should I say, whilst) seeking out some nutmeg a man approaches me and asks if he can have some advice about laundry detergent (with a very obvious Texas draw). When I agree to help he acknowledges that I 'speak' American. I smile, recommend a brand, and ask how many loads he'll need to do. Once that is settled I then attempt to explain to him to put the washing powder into the drawer of the clothes washer and about how when we first moved into our flat I had to ring up the letting agent to ask how to even work the thing...

He just grinned, thanked me and walked away. That's when I realized I answered in BRITISH! Yikes (blimey).