I have ran T&D streets at higher spring loads than that without issue, so I don't think it's the spring load.
Without knowing exactly which lobes they are, I don't know if I could recommend backing the springs off. There are some small duration Comp lobes that are very aggressive and need all the spring you can give them. Normally, as a general rule of thumb, I match the lift to the open spring load and then tweak from there.
Excessive lash could have done what you're seeing. Solid rollers are pretty violent if you get things out of spec.