Thanks for the tip!
Before I read your response, I saw on clearadmit.com that a follow up note is necessary, but that e-mail is preferable because a written, mailed letter may not get to he interviewer until after they've submitted their comments to the adcom.
Consequently, I already wrote a brief thank you e-mail, reiterating my interest in the program and referencing something personal that we talked about. I would have preferred to send something in the mail, but wanted the interview to get my follow up as quickly as possible in case she was submitting comments to the adcom.
Now that I read your reply, it sounds like I should have sent a hand-written note instead.
Question: Should I ALSO send the hand written note even though I already sent an e-mail, or would that just be plain annoying to the interviewer? If sending a hand written note is necessary in addition to my e-mail, should it say exactly the same thing? I'm afraid to sound like I'm begging for anything in these letters, so I kept my e-mail short and sweet.
Thanks for all of your help!