The only questions I can think to ask:
Did you utilize standard gasket sets only when you re-assembled? Did you use any other gasket/sealant material during re-assembly.
How about any heavy oil, grease, or other lubricant in the cylinders, pistons, bearings, that could have gotten in there?
Some crud could have gotten into the cylinder to produce a temporary elevation of the compression. As soon as the surpurfluous material is burned away, the compression SHOULD go back to normal.
