In all three cases, the answer given was one that exonerated the questioner completely, however unlikely it may have appeared to be.
Source: http://e-daf.com/index.asp?ID=377&size=1
(I would include the entire first story, but I am such a slow typist it would take me half an hour probably.)
We do see in the case of Gedalia ben Achikam that even though he did not have to accept as fact that the plotters were going to assassinate him, precautions should have been taken.
Gut Shabbos to all.