Cause of leaky pinion seal?

[shelby987]

I pulled my pinion yoke because I noticed a small leak, after about an hour and a half with a hammer, a slide hammer, and a two jaw gear pulled I finally got it off. I looked at the seal I pulled out, it didn't look too bad, didn't notice any big cuts or anything. Next I cleaned up the pinion yoke, and noticed that there is some surface rust and gaulling on the surface closest to the dust boot, I included a pic, its not too clear (camera sucks), is this the cause of my leak? If so, is there anything I can do with this yoke?

There also seems to be a groove about 1/8th of an inch up from the flat surface that is parallel with the dust boot, not sure if this is from debris or the seal, not sure how far forward the seal sits on this surface once installed in the case.