Welcome to the forum!....
Welcome to the forum Mat.....glad to see you bought a nice machine!...you should have tons of fun.
Normally, accessories are not part of any purchase agreement. But like daggerjon said, it is something you bargain for. During the time you were negotiating the price of the Doo, you had thought about it for a minute, then looked at the guy and said, "hey, I think your price is just a bit high, but guess what, you throw in a cover and I'll buy it"...........I'm sure, to get you to sign that loan form, he'd have jumped up and asked you what color.
Now, with the loan a done deal...........you'd be hard pressed to get any thing from him. That's just how business is done these days.
You may go in and talk to him and let him know how concerned you are about the elements getting to your new Doo....he may work a deal with you on the price.........but I doubt you'll get a "freebie" now.