Thats normal, and usually will occur if the 'crust' on top is disturbed. You can try skimming it off as best as you can. At some point, the brine can also be replaced with fresh.

Update: All of my pickles were coated in a whiteish slime. When I attempted to check for crunchiness... they would explode!!!! Batch number two to the compost pile :-(

My Mom had this happen to her once. It turned out she had used cucumbers that had been waxed. Could this be your problem, or did you grow your own cukes?

Lynda, I bought the cucumbers at our local fruit stand. I thought they were "wax" free. I'm so frustrated with my pickle prowess (or lack there of)...

I have one last chance to make a go of it this season, any words of advice from a Grand Pickler would be very welcome!

I'm pickling cukes for the first time myself. On the 12th day. So far so good. The one thing I did by mistake, that may or may not be good, was to slice the cukes in the beggining. I didn't read closely enough that the first week they should be soaked whole - then sliced. They seem okay though. Smell great. Seem crunchy enough. I'm keeping my fingers crossed that they will hold up to the processing.

Pickling cukes are a lighter green color one the stem end, to almost a pale green at the blossom end, and are much smaller than those big waxy cousins. Explosions, or swelling are common if they are waxed, or are old. Sometimes even insufficient salt in the brine can cause the batch to fail. You must also cut off at least the blossom end on each prior to filling a container. Chalk it up to a bad experience. If you have room outside, try planting some picking cukes next spring/summer. You can't get fresher than that. Who knows how long they sat at a store ot farm stand. If they seem rubbery, pass them by. Also avoid this long plastic wrapped English cukes as they are not designed for picking of any kind. I have 3 half gallons of half sours in my fridge. I made these back when my cukes were ferst bearing in the middle to end of June. I planted 4 types this year, and all were similar in shape excecpt the one with a lot more spines and a shiny skin. They are on the plant in the morning, and by the same afternoon are in a salt brine, or made into dill pickles with vinegar. These cukes can grow to picking size, almost overnight. Once you see some an inch long, they will be gainng size by at least an inch or two every day. Lots or water for the roots are very necessary.