Shouldn't happen. Apparently, it has. First time in 10 years, though, as far as I'm aware.
The homepage queue is managed automagically so that there are at least 5 clear shots between any two shots by the same photographer. A job runs each night to re-order the queue. To do that, it relies on there being a good enough mix of shots that it can actually sort them that way. Normally it's good out to at least 48 hours after the job runs.
In this case, it appears that a large number of uploads (and hence screening for the homepage) from one photographer has coincided with a lull in uploads from everyone else.
Let him that hath understanding count the number of the beast:
For it is the number of a man; and its number is One hundred threescore and twelve.