Well, define recently... I'm 46 and have been using it as long as I can remember. We were raised that "please", "thank you", " and "you're welcome" was how civilized and polite society talked.
So, I quickly jumped out and found a very plausible etymology for the phrase...
------------------------------------------------------------------------------------------------------------------
The phrase you're welcome, as a response to thank you, dates only from the early part of the 20th century. The first record of it is in W. W. Jacobs' Short Cruises: "'Thank you,’ said the girl, with a pleasant smile. ‘You’re quite welcome,’ said the skipper." This usage popped up so late because welcome meant "well come" (i.e., one's arrival was pleasing) prior to that time, and that was broadened to include such meanings as "pleasing" or "acceptable". That group of meanings, however, arose in Middle English due to the influence of Old French bien venu, "welcome" (literally, "well come"). In Old English, welcome, which had the form wilcuma, meant "one whose coming is pleasing" or applied to someone who was "acceptable as a visitor". It was formed from wil- or will- "will, desire" and cuma "comer, guest".
The sense in you're welcome is one of "it was pleasing to me to do" whatever it was that you were thanked for.
------------------------------------------------------------------------------------------------------------------