I was collecting berries and put some in a barrel. Suddenly there was a villager effect above the barrel, and I broke blocks under it and found no villagers. I was able to repeat this several times as shown in a clips I recorded. As you can see, I cannot figure out how or why this was happening. This took place on my survival world that has no addons or texture packs of any sorts.
You are sure that you have no villagers nearby? if not then It is a glitch where villagers from hundreds of blocks away have enormous detection ranges. The only harm this will cause it if you find the villager that has linked to your barrel, as the villager will have a bed in the village and his workstation at your base, and he has to travel far.