Prius c, strut assembly single top mount nut install issue

i was doing the front brakes on my daughters pain in the butt prius c, and noticed one of her front struts leaking oil and creaking and binding. so i popped in a pair of complete shock assemblies. these prius c have only one single top mount nut instead of the regular three top nuts. i don't like it. anyways, everything installed smoothly, new links, double checked everything i touched, tightened top nut under load (jack under lower ball joint) and here's my issue:

when i turn the steering wheel side to side (still up on jack stands, I'm waiting for more parts) i hear clicking. investigating this, if my hand is on the top nut i can feel the click and even see a wiggle. is this normal? i tried loosening the top nut, jacking back up, and retorque, same thing.

please if anyone has done this job and can advise, i would be very grateful!