Based on the timelines - I don't think it was IBD.
And then all the other balls that got sick - this went on for MONTHS according to her timeline.I quarantined her from my other four Balls for six weeks
It's my understanding that IBD is extremely aggressive in pythons, and that once a python is exposed to it, will kill it in under 30 days.
In fact, like it or not - and probably a dirty little secret, many boa breeders will "test" individuals their collection by housing them with a normal male ball python. If the python survives the 30 day "trial", they conclude that boa is not a carrier of IBD.