Michael Guerin <guerin(at)rentec(dot)com> writes:
> Is this message the sign of trouble, or is it harmless?
It's not good. The least bad explanation is that you had a system crash
recently that occurred between extending a table by one page and filling
that page with useful data. (The page is filled with zeroes on creation.)
If you haven't had any crashes lately then I'd wonder about whether your
disk is dropping data.
regards, tom lane