Sounds like, from your description, that you have restarted the fermentation. While you can remove some of the must to try to keep it from overflowing into the airlock, obviously this is something that you don't want to happen again in the future.
We've said it before in earlier posts, but it bears repeating again - Potassium Sorbate is a necessary, but not sufficient, ingredient in the chemical mix to completely stabilize a sweet mead. Sorbate forms sorbic acid when dissolved in a mead must, and sorbic acid acts as a form of "birth control" for yeast cells. It prevents them from successfully budding and forming new daughter cells. However, it does not kill currently active cells, so if there were any active cells remaining in your must when you racked over the fruit, they just happily began chewing on all the sugar that the fruit brought along to the mix.
Sulphites (actually the molecular sulphur dioxide that forms when sulphites are dissolved in a mead) will kill active cells once you reach their toxic threshold concentration. Many wine yeast strains can tolerate a lot of sulphite - upwards of 300 ppm if the fermentation is at the peak of the active phase, so you'll want to add sulphite only after the fermentation has all but finished. At that time, an addition of both sulphite and sorbate will do two things: 1) it will kill most yeast stragglers - those cells that for one reason or another hang around even when most of the fermentable sugar is gone, and 2) for the few that survive, they will be prevented from ever reproducing so even if they continue to ferment a bit longer, there are so few of them that they won't really do much before they finally expire on their own.
There is another reason to add sulphite along with sorbate in any mead or wine that you want to stabilize, BTW. In addition to providing the "one-two punch" that should prevent any refermentation from starting, the sulphite will also kill malolactic bacteria. You need to ensure that malolactic cultures do not start digesting the sorbate that you've added. If the MLF bacteria go to town on your sorbate, the result is a nasty smelling chemical called geraniol (similar to the aroma in citronella candles), that will never break down and will effectively spoil your mead.