Seeds could have been wild or spilled from something else in shipping. Probably weeds, but I've gotten some pretty cool plants from hitchhiking seeds/spores before. Diastema racemiferum, Anthurium scandens (I think), several ferns, Chlorophytum amaniense, and some other things I can't think of right now.

hmm...this is a little off topic but Heres a plant that popped up LITTERALY out of nowhere in the aquatic section of my lizard terrarium: I think it is a bladderwort or waterwheel plant, as whatever it is it has small traps.It also has small, feathery leaves. I guess I will have to wait until it flowers to see what it is.
P.S. Dont ask me to include a picture as the leaves and traps are so small on the photo that the plant looks like a green line!