To my knowledge, the initial reaction of a doom town is responding to noise and sending zombies to where the noise originated (you can see this is if you take a bunch of snipers near a doom town, shoot zombies until the town spawns zombies, then run away. The horde will stop exactly at the spot there snipers had been at
Given I was just shooting bows like 20 tiles away before the lookout tower went up I really doubt the town reacted to that. But I've never seen a doom town preempitvely belch out a few waves..