So earlier today I spawned 2 Wardens, and successfully avoided both of them. However, when. It seemed I had successfully snuck away, I stood still and waited for several minutes, and neither of them despawned.

They were both stuck on cliffs, and even though they were both calm it seemed like they were still trying to reach me (despite the fact that i should have been well out of sniffing range), but they couldn't pathfind a way down the cliff.

At one point I walked about two hundred blocks away and only then did they despawn.