It will not cause any more problem than the residue that it will leave behind on the frames, It doesn't seam to effect the bees from raising brood and storing honey in the combs.
Ideally in areas where we get a mid October to end of February winter. It would be nice to treat in the middle of August so the bees that emerge from the 1st part of September and latter, are as free as possible from mites and the effects they have on the colony. But the weather does not always cooperates. It is a trade off between treating early, and waiting till it is cool enough that you are not causing more damage to the brood, bees, and queen, due to it being to warm.