Thats a good idea about having them sign it and return it ..I do have companies that send me work a few times a year so there is not much comunication, and there are some companies that I talk with often and I know that they receive notice and I still get fed-ex .  Sometimes it is because the company is so big that everyone does not get the message. 
and yes I feel guilty every time I  take off  but I have two teenagers that  I take on vacation every spring break
Pam