Upon some investigation, it appears that I'm not the only one. A thread has started gaining speed on the official FarmVille forums filled with farmers just as confused as I as to where this free horse came from. Placing it on my farm caused no out of sync error, and it seems to work as normal. Heck, even multiple game refreshes didn't cause him to vanish. Sure, I'm excited, but the thing is, this Pony normally costs 24 Farm Cash, and that's a heck of a price tag for Zynga to suddenly release one to players for free, so forgive me for being skeptical.
What's more, not everyone has received this free animal. It could be that it simply hasn't rolled out to everyone yet, but it could also give further evidence to this being a glitch. In cases where items were simply given away, we normally received some sort of a pop-up as indication that it had happened, but this has silently come and gone without a peep from Zynga, as of this writing. Let's just hope that if this is a glitch, we won't suddenly lose our Dartmoor Ponies just as quickly as we were given them.
Are you one of the lucky players to receive a Dartmoor Pony in your Gift Box? Do you have any idea where they came from? Speculate with your fellow farmers in the comments.