naw theyd be the proper size.
if the bindings were coming off race skis, more likely than not, the screws will be the proper length for mounting the bindings with the ~1/8" risers made for fks bindings.
since im assuming that you dont have/dont want to use the risers, those screws that you have would be 1/8" too long because of the lack of riser, and therefore, 1/8' too long for the ski. use those screws and youll likely deal with dimpling in the base. ya dont want that.
i would bring them to a shop with experience mounting that binding. it was made for a reeeeally long time, so they usually will have a whole mess of leftover screws for them. or, if not, you could grind the screws down, just be sure not to overdo it.