Oh, no, Lybo..I've done the same thing, depending on the case...I just meant that you are entitled to be paid up front if you choose, and people understand that custom work cannot be re-sold in many cases, so they are willing to pay in advance.
Heck...most of my custom orders, I don't ask for ANYTHING until I can photo the finished item and see if the buyer likes it, but that is because so much of it is one of a kind. If I know I can't sell it to someone else, though, I do get paid in advance.