Have you noticed that employees don't say "you're welcome" these days? Most of the time it seems to be "no worries," which wouldn't bother me if I were Australian, but I'm not. I'd have no issue if they said "my pleasure." I might even prefer it. It's all about courtesy. "No worries" just seems way too indifferent to me. In courtesy, it's always better to take the high road. "I'm so glad I didn't cause a problem or worry you," should not be what you are thinking. Instead I want to feel glad I was there. Wow! She said it was her pleasure. How nice!