F800GSA INTERMITTANT FRONT WHEEL WOBBLE

I have a 2014 800GSA that we bought a couple of months ago. When I test rode it all was perfect. After we had paid for it I rode it back and half way back got a strange wobble on the front wheel, almost as if it was slightly oval. A gentle hopping. This continued for a bit and then went away. I put it down to something having been stuck on the tyre. It has done this on and off since then and I cannot fathom what is causing it. I took it into Tracmac and they balanced it as it was quite badly out and again seemed OK for a while. On a ride to Pringle Bay from Cape Town it felt awful. It has midlife Anekee 3's on. Any ideas?