You have either over filled the engine with oil- in which case you need to check the level and if it's too high you need to drain off the excess.
More likely is you have tipped the mower on it's side recently to either inspect or clean the underside- and possibly move the blade whislt doing so. If this is the case then the engine oil has started to migrate from the sump and into the exhaust. Only thing you can do is run it until the excess oil in the exhaust has burnt off (normally 5 minutes or so) and then clean up the the oil that has dripped on to the chassis with a rag.
pleasant, August 2008
