Good to hear you are still gaining pond elevation. When ballpark calculations are the best you can do, it is nice to have the data still fit within the ballpark.
I agree that the 9/16" loss doesn't sound too bad.
Since that pumping break was made subsequent to the water elevation rising, some of your water loss was due to the wicking of water out of the pond and into the dry soil that had just recently come into contact with water.
You can easily observe this phenomenon once you resume filling the pond. Depending on the clay content of your banks, you will probably see wet soil roughly 1-8" above the water elevation.
