index leaks ?

Hello,
I'm watching a strange beahviour by postgres,
I wonder if it's a memory leak:

Creating an index and destroying it makes the
postgres process grow in size. This is what I do:

create table test (a int);
create index test_idx on test (a); drop index test_idx;
create index test_idx on test (a); drop index test_idx;
create index test_idx on test (a); drop index test_idx;
...

The size growth is reported by 'top' in the fields
SIZE, RSS and SHARE.

The database is a newly created one after first initdb
as of CVS 20040311.

Can it be a memory leak in postgres code ?

TIA

--strk;