What should the voltage be on my Lifepo4 cells, after being fully charged and....

I think there are several possibilities. First, it depends on what you mean by "fully charged." I used a so-called smart charger before I got my balancing charger. That would shut off when the cells were around 3.6-3.7v, but then they would all settle back to 3.3x overnight like yours. Using the balancing charger they stay up at 3.5-3.6 overnight. But I think some of that last little bit is a surface charge. I checked it last time I rode and within 1/10 of a mile all cells were in the low 3.4s. But then they stayed in the low 3.4s to high 3.3s for some distance. I frequently go 10 miles or more before mine drop into the 3.2s, and then they stay in the 3.2s for another 10 miles or more.

Probably of more interest is how they hold up: do the low cells stay lower than the rest or is the pack in reasonable balance at 40/60/80% DOD? Are you getting good use out of the pack? - jd