I Never got a confirmation in the mail either. And, I had lost my confirmation number (not too good!)...but I called them back to add a day....and was basically holding my breath waiting for her to say they had my reservation (they did!!). I did add the night...but I haven't gotten a written confirmation yet...still....but I did copy down the confirmation numbers...in several places!
So...I'm sure it would be OK, but I do wish I'd get the hard copy of the confirmation. By the way...i booked in early May for August, and I wasn't billed for the first night untill July 1. When are you going?....maybe they are waiting till it's closer to your trip to bill.