I got this today reported by pichniche:

Approvals at Shutterstock 398 to 401

and then, about an hour later:

Approvals at Shutterstock 401 to 398

I didn't restarted computer or firefox in the mean time.
Anyone had similar experience?

I checked my SS port and
i have 398 approved files, although, I don't remember how many I had this morning.

Heya Ivan
Have seen similar a few times, it's rare, but it happens. I assume it's just SS reviewers just changing their mind (maybe training a new staff member), or the system taking a while to catchup. SS operate a cache of most of the user stats (updated hourly I think), so having small changes like that isn't too unusual.