I checked the lens mount today, and couldn't really find anything wrong with it. So I finally did a film plane focus check, and realized I screwed up. Infinity was at the twelve foot mark on the lens scale, so I knew I had to open it back up, and reverse the 5th element.
So, you were right, Pan. I got too confident in my ability to determine the correct orientation of that element going on previous experience. Maybe it's time I invested in one of those little suction cups for removing lens elements, as it came tumbling out while I was dismantling the lens. With my luck at playing the Lottery, I should have know I didn't stand a chance of getting it right, even with 50/50 odds.
It's back together now, so all I have to do is film test it again.