C30 Dana 70HD issue

[SCOTI]

I serviced the rear brakes last year as part of my rear suspension upgrades & correcting very poor braking (no rear brakes). I replaced the drums, shoes, hardware, hub bearings, & inner + outer hub/axle seals.

Fast-forward to current day & I was swapping new tires into place when I noticed a very small puddle of fluid that accumulated inside of the pass rear tire that had trickled down from the the drum.

At first I thought it might be brake fluid but it was rear end lube. So I pulled the drum/hub again to inspect the seal. The seal surface area looks fine w/no signs of damage. The rubber material wasn't damaged or mis-shaped. So, I pulled the seal to inspect further & the internal tension spring was damage free as well.

I'm @ a loss as to what the remedy needs to be here. The seal was a quality manufacturers brand & not the cheap house brand. It seemed to fit the rear end hub snount properly (slight interference fit/was not loose).

What steps can I take to make sure the repair is succesful given the fact that there's no obvious reason for the initial failure? Any useful suggestions?