I am inclined to agree with you. This is the first bb I overhauled with cotter pins and it is the first time I have had a problem. Looking at it again I see the spacing is not quite accurate: the way the crank arms are positioned on the bb spindle.

Steering still has me puzzled. The headset lines up with the seat post but there is the appearance of problems with the fork(s). The front left side dropout seems a tad higher than the right (although there is no indication of misalignment of the forks themselves). Would not that create a castoring to the left instead of to the right as is the case?
The rear dropouts may not be perfectly parallel and the axle nut on the left side has to be right at the forward limit of the dropout to have the wheel aligned between the chainstays.