I have seen this several times already (also on other SE sites), but only captured it in a screenshot now.
The question shown below came up in the "active" question view. It shows that user Robert performed some activity on the question five hours ago.
However, when I go to the question I don't see anyone named Robert that left a comment (or performed another activity) recently.
So what does this mean? Is it a bug? Is it a feature I don't understand?
p.s. I am sorry I picked a question of myself, it's not to boost views, just a coincidence.