When you check the oil - prior to starting the engine - pull the dip stick out, wipe it off and reinsert. Screw the cap down all the way. Now remove the dipstick to check the oil level. The tractor must be level when checking oil. When the engine sits overnight, oil walks up the dipstick on the opposed twins. The oil in the crankcase is probably still at the original level. I believe this is called Capillary action. The molecules in the oil are attracted to molecules in a solid (dipstick)causing the liquid to rise.

The Briggs opposed twin has been a very good - long life engine and is probably the most powerful engine in the small tractor industry. Most of these engines were equipped with splash lubrication. Your engine, however, is one of the premium models that is equipped with full pressure lubrication. An internal oil pump supplies oil to an oil filter and then to crankshaft bearing surfaces. Murray has been one of the low cost manufacturers and their use of a premium engine is surprising.

Smell the oil for the presence of gasoline. Sometimes the needle valve in the carb leaks and the gas ends up in the crankcase.
And get rid of the FRAM filter:-)