pistils won't be white within a day or so of pollination... if you see pistils darken way too early, that'd be a sign. Also, if heavily pollinated in any location, the development will be significantly less. it'll stop building bud sites and focus on developing the seeds. This sort of reaction is compartmentalized on the plant. It has no CNS.
lone nanner? no problem. Might find a seed or two.
An entire pollen sac - if open and mature you likely have pollination.