regexp_matches() quantified-capturing-parentheses oddity

Hi all,

wisu-dev=# SELECT regexp_matches('quux(at)foo@bar.zip', '([(at)(dot)]|[^(at)(dot)]+)', 'g');
{quux}
{(at)}
{foo}
{(at)}
{bar}
{.}
{zip}

So far, so good. However, can someone please explain the following to me?

wisu-dev=# SELECT regexp_matches('quux(at)foo@bar.zip', '([(at)(dot)]|[^(at)(dot)]+)+', 'g');
{p}

wisu-dev=# SELECT regexp_matches('quux(at)foo@bar.zip', '([(at)(dot)]|[^(at)(dot)]+){1,2}', 'g');
{(at)}
{(at)}
{.}
{p}

wisu-dev=# SELECT regexp_matches('quux(at)foo@bar.zip', '([(at)(dot)]|[^(at)(dot)]+){1,3}', 'g');
{foo}
{.}
{p}

What's going on here??

Regards,

-Julian Mehnle