Those compression numbers sound like our Lyc 0320 E2D powered 172M.
It never has had particularily good compression since it was new 25
years ago. If we get one that won't make 60/80, we check it again 5
or 10 hours later and it always is up again. It has been doing this
to us for 20 years.

I've always felt that a moderately (say 50/80)low compression number
without any other obvious cylinder trauma isn't automatically a reason
to pull a jug, at least not without a later recheck. If there are
other signs like high oil consumption, plug fouling, or rough running
etc then I could see pulling it.