age() vs. timestamp substraction

I just found this problem with the age() function, which AFAIK should give the same resulte as a subtraction of the argument from now(), but it doesn't.

prueba=> SELECT (now() - tc.last_cron),age(tc.last_cron),tc.intervalo FROM tareas_cron tc ;
?column? | age | intervalo
-------------------------------------+-------------------------------+-----------
@ 1 day 15 hours 13 mins 12.06 secs | @ 23 hours 59 mins 58.47 secs | @ 1 day
@ 15 hours 13 mins 12.06 secs | @ 1.52 secs ago | @ 30 mins
@ 15 hours 13 mins 12.08 secs | @ 1.50 secs ago | @ 10 mins

prueba=> SELECT version();
version
----------------------------------------------------------------------------------------
PostgreSQL 8.1.3 on i486-pc-linux-gnu, compiled by GCC cc (GCC) 4.0.3 (Debian 4.0.3-1)

Any ideas on why?

I starting to change my queries so they don't have the age() function anymore.

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Lic. Martín Marqués | SELECT 'mmarques' ||
Centro de Telemática | '@' || 'unl.edu.ar';
Universidad Nacional | DBA, Programador,
del Litoral | Administrador
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