Actually your story points out a pretty good fact. I'm a firearms instructor. Normally when someone has an AD at the range its normally one thing. They had their finger on the trigger. A few have managed to shoot themselves in the leg while holstering because they had their finger on the trigger.
In the field especially when pushing through thick brush unless you cover the trigger guard with your hand a stick getting in the trigger guards is very possible. Always a chance that the safety gets push off as well depending pon the type/style of firearm.
