I'd check the the tightness of all the nuts/bolts. On the last page of the instruction, right before they thank you for buying their product, here is what they say.
It is the buyers ultimate
responsibilty to have all bolts/nuts checked for tightness after the first 100 miles and then every 1000 miles.
Grease everything up real good and check the torque specs.
How long has the kit been on the Jeep? If it has been just a short while, chances are it will go way. Like a break-in period.