Here again, southern girl talking--I say "Thankyoukindly" ALL THE TIME since I started watching dueSouth; it only added 'kindly' to what i say anyway. "Sir" and "Ma'am" also are ingrained habit. We get a lot of northern transplants who don't use the honorifics, and it is unfortunately falling out of favor with kids EVERYWHERE. (I blame TV, and its blandifying of our regional differences, but that's a totally different rant.)

But my mom would have tanned my hide for being less than polite to a stranger growing up, and it sorta stuck.

(if it helps any, I use Brit spellings a lot of the time too. {grin})