The link you provided is broken so I haven't been able to view a picture. If it's just a single leaf that is much longer than the others it may just be a random mutation that occurred when that leaf was growing. It may still be Nymph Fly, especially if the leaves you received were "dark green, plain, pointed, spooned." Contacting the seller is probably your best bet if it turns out to not be the plant you ordered, as there are so many other plants that there is no way to definitively identify any of them, but the grower may know what it is because their collection will be much smaller.

Don't know what happened to pic, but here is the direct link:

http://i167.photobucket.com/albums/u127/imahoyaholic/Gesneriasds/plantsafricanviolet001.jpg