bool / vacuum full bug followup

OK, this is just beyond weird. I swear to GOD that my table size was
growing. I'm on a workstation that doesn't accept connections from
anybody but me.

I was running 7.2 for weeks.
I created a simple table:
create table test (buf text, yn bool);
I run an explain:
explain select * from test where yn=true;
I run an analyze:
analyze;
I update the table:
update test set yn=true where yn=true;
update test set yn=true where yn=true;
update test set yn=true where yn=true;
I do a REGULAR vacuum:
vacuum;

And after that, the table started growing after all vacuum fulls. I can't
reproduce it now. I blew away the table, recreated it, and now it doesn't
do that. I blew away the database, and installed 7.2.1 and it won't do
it. I reinstalled 7.2 and blew away the database and it still won't do
it.

So, I don't know why it WAS doing it, but it isn't now. And of course,
it's my personal workstation, so no log files. :-( I'll see if I can
reproduce this though, as I've seen similar problems pop up once in the
past with a seldom vacuumed database that reached a point where it stopped
freeing dead tuples. Very bothersome.