Thanks WJCO!Just looks like a little bit of seeping to me. Spray it off with brake clean and keep an eye on it. Make sure your fluid is full. I wouldn't worry about it myself unless it gets worse.
This is my experience also. For my part I know exactly why my pinion seeps...forgot to add rtv when installing the pinion seal after doing gears...two years later and never needed to add gear oil. Every time i check or change the level is still good.I had the same thing after changing fluids after 500 miles after regearing. Wet around the pinion seal, nothing on the ground. Fluid still up to the fill plug after a year. Not sure if that helps, but good luck.