OK, I get what you're saying now. Naavis is probably right: the next exposure is called for, then autofocus is called for and if AF takes a long time it deprecates the time to meridian flip. I wouldn't call that a bug but it is worth looking at to see if the order of things can be changed.
In any event, I highly encourage you to consider filter offsets and focus with the LUM filter. It saves loads of time. I simply can't imagine wasting all that time autofocusing. I understand that you may have good reasons for doing so, but I wouldn't have the patience.