No. Oil leaks are not common to Volvos. What happens is that maintenance of the PCV system is often ignored and pressure builds up in the manifold and starts blowing seals. I wonder if the tech made sure the small vacuum line to the PCV was clean, that can become clogged with oil deposits before the PCV is cleaned. Remove the PCV and take out the little plastic screen and throw it away.
To check for pressure build up, warm up the engine and loosen the oil cap. If it floats, there is too much pressure. It should be sucked down by the vacuum system.
Find out where the oil is leaking from. Hopefully, it is not the RMS again.

Klaus
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(V♂LV♂s 1975 164, 1995 854T, 1998 V70R)