'13 months ago'::reltime

Saluton,

I do not quite understand the following:

,----
| albert=> select '13 months ago'::reltime;
|     ?column?
| ---------------------
|  1 year 25 00:00 ago
| (1 row)
| 
| albert=> select '13 months ago'::interval;
|       ?column?
| ------------------------
|  1 year 1 mon 00:00 ago
| (1 row)
| 
| albert=> select version();
|                 version
| --------------------------------------------------------------------
|  PostgreSQL 7.0.2 on i586-pc-linux-gnulibc1, compiled by gcc 2.95.1
| (1 row)
`----

Shouldn't 13 months be 1 year and 1 month even for reltime?

Somewhat puzzled,

Albert.