I've kegged two batches and have had the same problem with both. I initially set the pressure to about 30 psi to force carb. After a couple of days, I purge the keg and then turn down the pressure to 10psi. However, when I come back later, the pressure has creeped back up to 30psi or beyond. It seems the beer continues to pressurize way beyond what I have the regulator set on. It's hard to get it to stabilize at the correct psi.