Thanks for reporting; I made some changes in the alpha that's about to go up (25) to the code that handles item security that should help - I'm not sure if it was the entire issue, but roughly characters had an easier time 'stealing' items than they should have (and from memory also did it more often than they should have). It might still need some tweaking, but hopefully it'll be a bit better.
Honestly, I really like the idea of characters stealing items, though there would definitely need to be a way to protect items, or at least a small right away, like maybe a vault building that can secure a small few items, but that would have to be available immediately if the player starts with items.