Obviously many teas benefit from re-steeping (not too mention it being
economical), but I'm curious about how and how long the leaves can be
stored between steeps.

For a decent oolong, 7 steeps is pretty average for me, but this means
that the tea is out for at least 2 or 3 hours. Is this okay? Do
the leaves go bad being wet and left out? Is there a limit? I
remember reading a while ago an inconclusive study regarding oolong
leaves that had been left out for a while and some bacteria (I
believe) growing in them that caused cancer among mice. (I know, it
sounds odd.) Has anyone else heard this and has anything been
substantiated?

Thanks!