Yes, the bearing cone and roller assy is most definitely a press fit on the shaft, however, if the hub is not bolted to the axle housing, it is free to flop around a little. In other words, there is nothing to force the hub (and installed bearing cup) towards the cone and roller assy until the hub is bolted to the trumpet housing. A fairly tight seal might be what made it feel snug.
I felt it necessary to correct you here so that others don't think that a problem exists where there is none. End play of either side cannot be checked until BOTH axles are installed.