I had a similar experience when I was in Detroit in '13. The GT Guys were working on my car when Dennis noted the same sepage at the front of the pump. As they had one in stock he swapped it out and we compared the two. The shaft for the pulley on the original one didn't have threads that went down far enough to for the nut to tighten the pulley properly. This one missing thread allowed the pulley to wobble very slightly putting uneven wear on the seal. The threads on the new one was noticeably different and the pulley snugged up tight when the nut was torqued down. I have my old one at the shop and will get a pic of the shaft to compare.
Since the new oil was already in before the belt swap they had to drain it all to change the pump. I believe I hold the record for shortest distance between oil changes. 0 feet horizontal, 6 feet vertical.