We do see things similar to this from time to time, usually when they are eating cake. I wonder if it's a ewe's reaction to having a bit of cake lodged somewhere. It seems to pass and they don't seem to do it again.
So it's probably nothing, but if you want to give her something, a good mineral drench will do no harm.
If she does it again, there may be a medical cause. There are diseases (CCN, Listeriosis, another one I'll remember as soon as I leave the computer

) which can cause strange gaits. Pretty much all of them are treated by antibiotics and Vitamin B. So if you think it's more than a one-off, you could give her a/bs and VitB.