I had the same exact problem with mine when I installed it. Seems that Mustang has a quality issue where they make the seat too long. I had to go back and forth with Mustang to make things right, but they finally replaced the seat. I don't have a picture of it, but I had the defective seat and the new seat in my possession at the same time and compared them, and I could see the difference in the length of the seats. The pics are gone from the threads, but you can see my comments about the situation here.

 

Here's pictures of the "bad" seat and the "good" seat.

 

^^^^^^^^^^^^^^
Whoa! That's amazing.

 

Never thought to look until I stumbled across this thread...I have a 4.5 gal tank and have the wrinkle:

 

Mine has the wrinkle too. . .I bought mine used but it's the right part number. I think the Nightster tanks are longer. It doesn't bother me much.

 

After having put some miles on it since then, mine still has those pesky nose wrinkles. So they don't go away after break in.

 

I don't think you'll have a problem selling it on ebay if you're not happy with it. I wouldn't wait too long though as those wrinkles might not go away.

I too have an '08 Nightster and after looking here, got the one for the 4.5 gal tank and it not only fits perfect, but looks like the original designer intended it.

Good luck with this. Hope it all works out.

Raz