This happened a few minutes ago:

And I cannot find the relevant post. Tried to reproduce by upvoting someone else, without luck.

This happens when you get an upvote in the developer journal section. You get the upvote here

This happens when you get an upvote in the developer journal section. You get the upvote here

Aha, I see, that clears it up. Thanks!

I was gonna suggest phantom possibly voted you up, just because that would seem appropriate, given his name and the blank log entry...