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
argumentfrom 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@
15hours 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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