Apfelwein with a head?

So I followed the standard Apfelwein recipe, stablized it, then added the brown sugar cinnamon part of Dave's Caramel Apple Cider. Bottled about a month ago. Just opened a swingtop of it and was greeted with a little foam-over and when poured into a glass it's got a velvety-smooth dense head that can support a bottle cap.

Now if I could be promised this upon every opening I'd be super excited. But do I now need to fear bottle bombs? I stabilized with 1tbl of sorbate and 5 campden tablets, which always worked before

Are you certain fermentation was complete and your wine cleared?

I was pretty sure. popped it back under an airlock for a few days after I back sweetened and there was nary a bubble.

I mean clearly it wasn't I guess.