I have seen the same miracle on Triglav's south ridge while descending in the clouds, on the last weekend. I could manage to unpack the camera, but had no chance to adjust it - and the miracle was gone... but it still lives in my memory.
So congrats for making such a photo!
I also envy you for your trips on the 'Horns!
My next summer plan is Weisshorn...
The optical theory behind it is rather complicated, but it sure is an awesome sight to behold, only since it takes clouds and moisture and low sunlight, hardly enyone has one's camera not tucked away at the right moment :)
I once saw both my own and my dog's giant likenesses, both with rainbow halos.