Reb it is common but not normal. I have a couple of Weaver V-3's(1-3x20mm) one has some fisheye on 1x the other two do not. One of my Leupolds 1-4x20mm scopes has some ever so slight, it's a VX-1, none on the VariX-II or VX-2. Neither my Nikon Monarch 1.25-4.5x20 or my Bushnell Elite 4200 1.25-4x24 have any fish eye. In 1.5-6x40/42's Bausch & Lomb, Burris, Alpen, and Sightron no fisheye at all. I did have a Bushnell XLT 1.5-6x42 that had fisheye at the lowest power. In 2-7 scopes I've only have had 2 a Weaver VR-7 and a Burris FF-II and neither had it.
In all those that had the fisheye none were bad enough to make them unusable at the lowest power, it was just at the outer third or less of the image and it didn't cloud the image it just distorted it a little, if you were focused on a coyote under the crosshairs you could still readily see a second one sneak in from the side or discern what was ahead of a moving coyote.
I think you find it more on low end scopes and if is more than just at the outer edge I'd send it back for a replacement and if they tell it is normal a refund.