realskiers

I would take the bindings off the rail and make sure that there isn't any real looseness in things that should be tight.  Look at the underside where the rail pushes into the plastic groove on each binding and make sure that nothing is really failing, and check the metal plate on the bottom of the binding that actually rides on the rail.  If those attachment points are tight then I wouldn't be very concerned; when you click into the binding the forward pressure is going to tighten things up.

I assume you are describing looseness in the binding to rail connection. The heelpiece is probably a diagonal release binding, and that does have wiggle when the binding is open.

I think the fit is normally loose, but not what I would characterize as "significant looseness".
And you probably would prefer not to have the bindings come loose from the connecting rail while skiing.
Since I know where those skis came from, if you notice significant  yellow stain coverage under the bindings, then you should dispose of them immediately.

By the way, I have an extra set of Railflex II rails and bindings I was going to dispose of.  I'll stick them in a box just in case you'd like to pick them up this summer.