Great shot Andy, but as others have explained, don't put too much stock in the bot. I don't understand it, but it seems to feed on itself and the more you're "chosen", the more likely you are to get chosen again. Some of what they choose go really viral, some don't. Like you, the first time I thought I'd had a shot chosen, I only found out because suddenly I was over-run by comments. Turns out I'd had four or five chosen previously that I hadn't been aware of. On my recent trip, when I was posting a lot and seemed to have a somewhat consistent band of followers, I had five of them selected in about two weeks. A couple of them were even pretty good ones! Which is another thing - when I go back and look at what they've chosen (which is up to 15 or 16 since they first picked one last April), there are a few I like. Even a couple that I'd rank among my best. But a LOT of them just make me wonder WHAT the hell those robots are thinking?!?!?!
Its also kind of funny to watch the behavior of people who comment and "favorite" your shots once you've had a few on there. Evidently, there's something about commenting a lot, particularly on other "explored" shots, that increases your chances of having something selected yourself. And in the past several months, I seem to have picked up a couple of followers who I have zero idea who they are, but who post the same meaningless comment ("great shot"!) seemingly randomly on my shots, usually on stuff that I think is the farthest possible thing from a "great shot".
In short, the whole thing is rather bizarre and meaningless. But the first time you get a shot getting hundreds of "favorites" and up around a hundred or more comments, it is a small kick in the ego until you realize how random it is!
You do great work. There MAY be a small correlation between that and getting recognized on Explore, but I don't think there's much of one... Just be happy with your work - its all that matters!
-Ray