The PCV CAN be the problem.  I have fixed many of them for the same reason.

If the PCV system is not function properly, it will not pull enough fumes out of the crankcase.  Instead, it passes backward out of the PCV inlet and out through the breather.  This is a bit messy, but does not cause problems.   When the inlet is somewhat restricted due to fume contamination, the pressure from the blowby (which all engines have) can't get out of the breather, or through the PCV valve, where it should go, and starts to build up pressure in the crankcase.  This pressure can cause seals and gaskets to leak.

You will often find the pressure build up only occours at high engine rpm or periods of somewhat open throttle.  At these times the greater pressure in the cylinder creates more blowby than the PCV system can handle.

The only time it builds pressure and leaks oil is when both the valve does not flow enough, and the inlet does not vent the excess blowby.

After market PCV valves do not always have the correct flow rate.  Discount part stores use one valve in place of several from the Mfg.  They are visually identical, and fit the part, but the flow rates can be different.  The after market takes an average flow and uses it to replace several applications to able them to stock fewer part numbers.  Places like NAPA have more numbers in stock, and dealers have more per vehicle line.   Flow rate is important.  Remember, a PCV valve is a calibrated vacuum leak as far as fuel mixture and intake is concerned.  A wrong calibration can change the fuel mixture, more noticable at low load and engine speed.  This can sometimes be corrected by mixture adjustment on the idle mixture screws, but not always,  and most folks don't check mixture when intalling a PCV.

Dont' forget to check the PCV hoses, filters, vacuum source, etc when checking the system.