how's my English

I thought it was funny during my meeting in Nottingham (UK) the other day when a man finished our discussion by thanking me and then saying, "It doesn't even feel like I'm speaking to someone bilingual. Your English is so good." I told him I was American and laughed inside as he walked away.

Yesterday when I spoke to my Mom she told me that she's noticed my English changing in my blog posts. At first I thought she was referring to my poor spelling (I am lazy and don't always check what I post...), which she was. But she was also talking about how I write and the words I choose. She said my English is becoming europeanized with words like whilst and pyjama (instead of pajama).

So now I'm wondering about my conversation in Nottingham. Is my English becoming so unnatural that even a native English speaker can't identify me as a native American speaker? I'd assumed he'd said that since, come on, who would expect to encounter an American working with European money? Or maybe he's just a dope....

Either way, it makes me wonder if one day I'll be one of those expats who has to search long and hard for words, whose accent is "mid-Atlantic" and whose spelling is atrowshiss.