[Bug?] Titan's Breath

Anticipating the Air Elemental casting Titan's Breath, I moved my sovereign away from the rest of my troops to try and avoid the AoE.  It didn't work  However something very strange happened - I got pushed off the edge of the map.  The red line shows where the end of the map lies, and as you can see I was forced beyond it.  

Is this intentional?  I would have thought I'd just bounce off the edge...