Was hoping this nasty little "feature" wouldn't make it into the game, but it's here alright. At level two I passed under the bridge near the vault and was assaulted by molerats. They were easily dispatched with two shots to the face (no crits). At level three I passed under the same bridge, and to my dismay the molerats were replaced by dogs which took seven (SEVEN) shots to the face (no crits) to drop. I wonder if the zombie dogs will be replaced by deathclaws at level four.