Well, those numbers are pretty close to normal for a less than new ping. So I don't see any red flags there myself. A newer one would hold the charge better, a really new one only dropping to about 56v. But once riding, you'd see about 52v not under load for most of the ride.
I'd say your sag under that load is not bad, so that's a pretty good indicator it's not having any real trouble. More likely the data a CA can best give you to estimate your battery health is capacity. My 15 ah ping with a few hundred cycles on it is just starting to show it's age, and now gives 14 ah to the bms cutoff. When new, it gave closer to 15 ah. So if you come up a full 5 ah short, then that would indicate one cell that died in at least one cell group.
THE LIPO RULES. NEVER ABOVE 4.3V NEVER BELOW 2.7V DON'T PUNCTURE
Ideal charging /discharging range for Lipo, 3.65v minimum 4.1v maximum
See battery technology section, FAQ thread at the top of the page for lipo noob info.