Hello everyone! 

I have a corgi that just turned 2 years old in June and I have never seen him do this.  He was just kind of walking around and then he started humping the air and trying to move forward at the same time.  He's neutered and he wasn't trying to mount anything.  It was like he was trying to walk but he had a spontaneous humping fit but he tried to keep on walking? For a split second he looked like he was trying to take a poop because of the way that he was hunched during the spasms, or whatever they were.  That's the only way I can think of how to describe it. 

It only lasted a few seconds and then a few minutes later it happened one more time, again only lasting a few seconds.  Then he just went about his business.  It's been about an two hours now and it hasn't happened again.  He's acting normal, he doesn't seem to be in any distress, and he's not lethargic or showing any odd behavior.  He ate this morning, went to the bathroom outside, drinking water--- everything else is normal.

I'm keeping an eye on him just in case, but I was wondering if any of you would know what it was?  An odd tic or twitch?  Is it something I should be concerned about?

Thanks for your responses!