It is normal for a small amount of oil to leak out of the housing of the trimmer when the trimmer is extended to it's full height for the first time. It is also normal to find a small amount of oil on the unit when the unit is turned from the trimming to the edging position for the first time.

This is a oil that is necessary to lubricate some of the internal moving components and if a small amount should leak out of the trimmer you can simply wipe the trimmer off. This does not usually occur after the first use of the trimmer.