It is very doubtful that anything bad happened when you cleaned the hair, in fact I would venture a guess that not ALL of the old rosin was removed. It takes me quite a bit of effort with 180 proof alcohol to clean my bow hair spotless. I use Bakers Rosin and have never had an issue with excessive powder problems.

Other rosins are more prone to dust as they dry out more.

I apply every time I play even if it's several times a day. I don't go overboard and slide the rosin 50 times each application, just a couple of strokes is more than enough for my situation each session.

Most rosins are quite compatible with each other but if you have a soft wintertime rosin applied and then go over it with a harder rosin "made for" warmer use in the hotter climates then perhaps you're not getting a proper 'mix' for the situation. I'd clean again really well, seperating the hairs as it drys, (shouldn't take more than 15 minutes to dry completely in the warm weather) until you don't feel any sticky residue on the hairs and then reapply my rosin. Remember when you've cleaned it so well, it's just like a new rehair job, it will take a LOT of strokes to completely coat the hairs enough.