The reason for the drop in bounty, I believe, is because HS is now using a setting called something like "NearDeathExperience." When you reach around 1/10 of your energy or lower, it is counted as a "Near Death Experience" and your bounty is decreased by 1. There will also be a small red flare that appears beside your ship. One useful purpose of this is so you can tell when you've almost killed someone, even without Energy Scanner.