I think all the points on prep are correct and boy was my axle prepped! And I used all the POR materials and even wore gloves to touch the metal.
The thing was that I spilled polyurethane stripper on it and that caused the problem. I wiped it off and there were bits sticking up that I pulled and it peeled a little off.
Im still confident in the por 15 though I feel it is slightly less tough than the rust bullet--just my impression, but I wont be pouring stripper on it to test the theory--sorry!
Here's some pics of the POR it does look nice going on! I'll post some of the rust bullet on the frame when I get some more progress