The question would be whether it is coming from the transaxle or was someone a bit over zealous in greasing the axle before putting the wheel on. A light to medium coating over the axle is all that is required there. You may want to clean the area and monitor to see how much lube is appearing there. It isn't so uncommon to have a Foote manual seep grease out through the sides on some manual transaxles due to the poor seal around the shaft. On the other hand- a hydrostatic model that is leaking lube may be in need of attention -depending what model it has. A model # from below the seat would be helpful for more info on this.