Unless the lifters have oiling holes too, then it's not an issue.

If the lifters do, then possibly that is your issue. 10 Psi is on the low side, but still above spec, barely. What weight oil are you running?

I prefer to run 10w30 myself.

They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.