As the topic suggests, try to take the few extra seconds and load the ox pack back on the ox after you are done with it. Just today I've seen two open ox packs lying on the ground around Hlint.
There are quite a few good reasons why taking care of your own ox pack would be good manners.
For starters, no reason to tempt the wannabe thieves. Stealing is against the server rules, but you should not carelessly create situations which would allow it.
Also even if you do not worry about it, other people do. Just because you didn't bother loading the pack on the ox someone else might spend quite a while trying to track down the owner of the ox and it's pack.