But for your theory to make sense, you'd have to actually believe that while she's answering your emails, she stops, says to herself, "oh yeah, this is a text to Sjkero, so I have to close it differently", consciously makes the decision to use a phrase that somehow she knows magically makes you feel differently. Maybe she just likes to switch things up in her own writing from time to time? Maybe it is a short closer, and she uses it in quick emails simply because she's answering them quickly. I suspect she doesn't give it a second thought. I don't think she's sitting there agonizing on which phrase to use in the closing to an email.