I was just doing some random searches to see if there were similar products to what I was creating.  I was able to to easily check that that image hadn't had any extended license sales, so I gave them a  call and I just remember being really surprised when I got a real person on the line fairly quickly (and I was at night if I recall correctly) they were very pleasant and eager to help.  Then next day the product was gone.

I've also noticed on quite a few stores that use clip art type images you will see the store owner posting a message about using properly licensed clip art and a link to the artists whom they have deal with.

I'm wasn't exclusive so I had to check a couple of sites.  The extended license terms are slightly different everywhere but at the time I believe at least one of the sites I was with allowed print on demand use in a extended license for resale.  The image in question hadn't had anything but standard sales so I was sure it wasn't legit.  I don't think resale licenses that allow POD are very common.