postgresql regular expr bug?

Hello

can somebody explain this behave?

postgres=# select '10' ~ e'^\\d+$';?column?
----------t
(1 row)
ok

postgres=# select '10' ~ '[0..9]+$';?column?
----------t
(1 row)
ok

postgres=# select '10' ~ '^[0..9]+$';?column?
----------f
(1 row)
?????
postgres=# select version();                                             version
---------------------------------------------------------------------------------------------------PostgreSQL 8.3.7 on
i686-pc-linux-gnu,compiled by GCC gcc (GCC)
 
4.4.0 20090506 (Red Hat 4.4.0-4)
(1 row)

tested on fedora 11

Regards
Pavel Stehule