They may. A lot of things affect ear carriage. A rabbit with a narrow skull, largish ears and relatively weak ligaments on its ears may develop lopped ears, even if it has no lop in its background (English Angoras are bad about this; I've had it happen to some Harlequins, too, particularly in the summer months). To get the vertically hanging ears that are considered desirable in a Lop, you need ears that are set wide apart on a wide skull to begin with. Years ago, we used to see a lot of young Holland Lops that did a sort of "ear semaphore" - one up, one down, or both halfway; even a lot of the good ones went through the "helicopter ears" stage where they still had ear control. Most of the better bred lops have ears that go down at a very early age. A rabbit with the type of skull that one would expect from a Mini Lop/Mini Rex cross might not have ears that come above horizontal, but I wouldn't expect them ever to be completely vertical, either.
Ok thanks. He sooooo cute!