question about the 0320 oil press relief valve.

I have an o-320d 1A on my -4. I have noticed as it aquires more hours the oil press has dropped slowly. I tweaked it up about 20 hours ago and it slowly dropped again. Today I looked at the relief valve and I appears ( looking at the unpainted threads in it) the shaft is backing out. Has anyone ever seen this before?

about 830 hours since new.

I have searched the forum but didn't see this mentioned.

thanks

Chris Murphy