Where is the line...? or How would/do you respond...?

[Arthur Banks]

I have a future tenant who I've conversed with on a few occasions via email and text.  The question I have is, where do you draw the line with friendly comments/remarks?  For instance, she concluded an email the other day stating "I hope you're staying warm and enjoying those Bulls wins." GO BULLS!!! I was stuck on whether to reply to that comment or not.   Not just because of that, but she commented on my facebook page of about the rehab job we did on her place.  She checked out my LinkedIn page.  I don't have any issues with her doing her due diligence on me.  In fact, I welcome it. It says to me she wants to know who I am and what kind of business I run just as much as I want to know who she is.  So back to my question, where do you draw the line and how do you respond to such friendly chat/comments?  I want to make sure I keep it professional.  But I don't want to be stuffy either.  Oh, before anyone suggests, it's not flirtatious in anyway.