I noticed when you don't get arggo sometimes from mobs, they will arggo you X amount of time later, even Baf too.
For instance, I passed an Oj mob, and a drinker was on the opposite side (even out of normal arggo range), after fighting a few Mahr and Cath Spiders, I randomly got arggo from the previous Oj mob I passed as well as from two drinkers. These mobs were not in arggo range and from a completely different room at the time of arggo.
Delayed Arggo in DF
Re: Delayed Arggo in DF
Not all aggro is instant