Most likely, the avatar was near the edge of the sim (region).
There is a 34 meter boundary around each region where you're actually in two at once. This is done to ease boundary crossings and let you see and talk to people even though they're actually over the line.
Sometimes lag sets in, of course. It's possible for your viewer to think you're on the new region, but the old region still thinks you're there, too. If, during this brief period, the cat is dropped, the old region will quite happily take control of the object.
Now, you cat wants to teleport Home, and Home happens to be on that region. It can't do that all at once. It need to move in fits and starts, working its way IN A STRAIGHT LINE from where it is, to where it wants to end up.
Usually, this works fine.
But, say you're up at 4000, at one corner, and Home is at 20 at the other. The cat needs to move nearly 8000 meters .. 100 or so at a time .. slantwise across and down the sim. OK, it can do that.
But, along the way, what happens if it hits a No Entry parcel? It stops! It can't go forward. So it sits, floating somewhere between 4000 where it started, and 20 where wants to end up .. on the line it wanted to travel.
*sigh*
Area Search is your friend.