1990 Nissan 300ZX door locks

just wanted to know if my doors were broken if i am able to lock them from the outside without needing a key by holding the door handle upwards while closing the doors after i have already locked them from the inside before getting out. i have seen some cars be able to do this before and i am just wondering if this is normal. because most doors lock after you have locked them from the inside on their own and if they don't you would have to use a key only. they lock fine with the key, like i said i was just wondering if my mechanisms were broken to have the doors to be able to operate this way?
[img:a0e4719aeb]http://www.2carpros.com/forum/automotive_pictures/266146_m_90103d669a9d56e86b73cc27185c3c72_1.jpg[/img:a0e4719aeb]