Don't worry Patrick, it happens to all of us. You know you've been here too long when you go back to the country of your birth and upbringing, and those who never left say "You do speak English well, where did you learn it?", thinking they are being nice to a foreigner.
In other words - one's gone a wee bit native.An Italian
once described me as "Germanizzato". Since we were discussing political economics, I chose to take that as a compliment.