Play Nice!

Of all the interesting or important stuff I could write about today, I selected this individual simply because of her incredible skill. I work a helpdesk job at a hospital and rarely do I have any problems with callers since they realize that being nice to me gets them better service and vice versa. So this call I receive today starts off simple enough, a woman is new to the hospital and needs to fax the I.S. department some paperwork so she can have access to a computer. After telling her that I only work weekends and that I don't have the access to give her what she needs, I politely tell her that she or her manager will need to fax the paperwork down during the week. She then says, "ok, well what is the fax number" and I reply back that I don't have a fax machine here in the data center so I don't know the fax number. Then, out of nowhere, in a very sincere voice she tells me, " thanks a lot, you've been a real help to me" and hangs up before I can get another word in. She should have just told me that I was a worthless and deserved to be shot in the head only to fall in my own grave from the tone she used. And all I did was try to help.....
This might not surprise many people who are used to situations like this, but damn, it rattled me a bit. Why would a perfectly normal, polite conversation end up going so wrong? Must be the holidays!