yup that is normal.

What substrate are you using? I find coco peat or coco coir aka eco earth to hold tons of humidity and unlike cyprus it re-wets easily cyprus once dried out fully doesn't seem to absorb as much water.

With a humid hide you should have no problems anyway with 51 isn't that far away from prefect sheds I have had perfect sheds as low as 54% so you are defiantly mostly there.