G’day Chris,
Your image is indeed the shock wave on the surface of the wing causing an optical distortion. It is usually more clearly visible on the wing that is into the sun and as you were flying on a westerly heading it makes sense that you could see it on the right hand wing. In your image there are two parallel distortions, the thicker more rearward one is the main shockwave and the thinner one just in front of it is a smaller shockwave called the lambda foot.
Here’s a previous discussion on the subject.
http://www.pprune.org/tech-log/25921...-aircraft.html
I first saw the shockwave on the wing of a B707 years ago when I was in the Aussie Airforce.
Regards,
BH