A "slight" pressure is ok, but it sounds like you have too much blow-by if the dip stick tube is venting with the valve covers vented also. I would run a leak-down test next. Then maybe put a few miles on it and run the test again to see if there are any changes. Excessive blow-by could just be because the motor is new. A pan oil leak would occur all the time - although more excessive at higher RPM.