If you installed the spacer properly, you should be fine. The bearings should require a bit of force applied to the outer race only in order to get them in. Seat the fixed bearing first, then install the spacer, then the "floating" baring tight to the spacer.
did you notice any slop when fitting the bearings? The should be tight, requiring a bit of force on the outer race only in order to seat them. If the bearing can be pressed in by hand or simply dropped in, then the bearing is the wrong size or the hub is out of spec.