Yeah, that would make sense. Whenever I have a bunch of elephants die, I always notice they get healed much more than other units. Most of my elephants usually get killed by missiles, and that coupled with having more hp would probably make them heal more than other units. And I've also noticed the missile thing with archer units. My Kretan Archers are never in melee combat, but they still take some casualties from other archers, and I almost never have my Kretans drop in number, even though they take casualties.