I've had a similar but different experience with debris in the mast, my situation was a very large mud wasp (some people refer to them as dobbers). pulled the mast in the fall for it's bi-annual rigging inspection to find the last foot full of mud, debris and several dead wasps. Only happened once in the mast but another time caught the start of a nest in the folds of the main on the 27 Cherubini we owned at the time.