I'm having the same problem with a recent batch. The head forms tight knit groups of tiny white foamy bubbles. The bubbles cling together in small groups and the groups almost repel each other, it looks weird if you watch closely, unlike any home brew I've made before.
The beer was 10# of pilsner malt with a Kolsch yeast and Saaz hops. Not sure if the ingredients matter but I can't think of anything in my process that was different from 2 recent batches which do not have this problem.