I am aware of the issue of chain voting and its reversal process.
However, in recent days I have seen several upvotes within a short time window (max. 2 minutes), 1 vote per post. This always happened at the same time of the day and covers recent posts of mine.
So while this is strange, the algorithm didn't reverse it.
As I am sure that others have noticed the same, it might present a considerable skewing effect on reputation scores. Of course there is the chance, that it is legitimately done by a user who browses my profile and then reads some of my recent posts. But nevertheless it should be looked into.