Sorbothane is always sticky, as the closed cell foam is filled with viscous fluid that leaches out. So your experience is common. The stuff my speakers released was fully dissolved sorbothane where the walls of of the cells broke down for some reason. Solvents can cause that, so maybe cleaners or aerosols or perhaps freon leaking in the HVAC caused my driver isolation rings to melt. I dont have the answer, but my current speakers are using highly compliant silicone instead of the more ideal material, sorbothane.Silicone shouldn't break down, but it isn't as effective for the task.