Did you insert a T-barb in there between the nozzle hose and reroute the flow for bypass? At 60 p.s.i. without a bypass flow, it would blow the seals or leak somewhere within the nozzle when you aren't continually using the apparatus. I am applying at 45 psi in my solo's, with the pump method, and they tend to leak at weak joints. There isn't enough teflon to keep these things from leaking at the wands.
I buy agricultural wands and without most suppliers using brass now, they are prone to leaking all over the place.