Julia M. Usher posted:
Ambient humidity can also affect drying time a lot. And if you have overhead or other fans blowing, the icing will crust faster. Could it be possible that you had different ambient conditions than usual as well?
Possibly. Same ambient conditions I've been cookieing with since I started using this icing recipe (winter/wood stove in attached living room) but I haven't been doing much wet-on-wet this winter either, so not much experience with it in these conditions.