Access to sys views from package body

Hi,

does it exist any limitation of using system views in procedures or packages? I noticed a following problem while getting the data from all_tab_comments:

query:

select count(*) from all_tab_comments where comment is not null and owner = 'test'  - returns >100 rows

PL/SQL Block:

returns the same

but ... executed from package body returns only 3 rows.

Thanks for explanations.

BTW. 11.2.0.2