Help with problem using wildcard in string value expression

(I first asked for help under postgres-sql, but this looks like it
isn't an sql problem after all.)

I've got a strange problem with wildcards (postgresql 7.0.2).

On some tables, the character combination '.%' in a pattern
prevents the pattern from every matching. But on other tables
the combination works fine. The attached script output shows
the problem. I see this in several different databases, but
so far only in databases with more than a few rows, and with
indices. This is a typical example (I've annotated the output
with a couple of comments, look for lines starting with "> ".

If anyone can explain (a) why I'm seeing this behavior and
(b) what I can do to fix it, I'd be eternally grateful.

Thanks!
--
Steve Wampler- SOLIS Project, National Solar Observatory
swampler(at)noao(dot)edu