Is there a reason why she kept this?

I have this friend who I suspect we might romantic feelings for each other. Sometimes at work we write notes to each other so we can remember certain tasks the other is supposed to do the next morning. She wrote me a note about if I could ask the maintenance man to fix the gnat problem. I wrote back that I would and she responded thank you and put a large heart next to the thank you. Then I responded back “welcome!” and put a smiley face.

Well the paper that we wrote all that on had been at the desk for over a week now and she hasn’t thrown it away. In fact she took it out, and put it in the folder pocket that sits at our desk. I wonder why she hadn’t thrown it away when she’s thrown papers away with other notes she’s taken. We both love writing and I have expressed that I love writing love letters. Is there a specific reason?
Is there a reason why she kept this?
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