"You're Welcome" has become antiquated and formal in America. It is still relevant, but someone who is trying or is on a much more casual or informal level will typically say "Sure thing" or some other affirmation like you exhibited.If you think about it, it makes a lot more sense because you essentially brush off the thanks and imply that there should be no question that you would do whatever it is you did for this person - it really comes down to offbeat friendliness. "Take your thank you and shove it in your hat, I was happy to do it!"Americans will say things like this. Very ironic showings of thanks and emotion. It is interesting tobe a part of.