Pine needles are magic, Tracy(M), they can get into places you cannot possibly imagine. My neighbor has one that I would love to kill....needles in my rain gutters, pool, deck furniture, etc.....
That must be it! The only other thing I can think of is there is a wasp (kinda like dirt dauber if y'all have those out there) that uses pine needles and like pieces of grass and such for their egg cases but sill can't figger out how the sumbitch would be getting in to it!
Doc, you need a buddy with a garage to do what I call a "lick and stick". Pull in hand him the paperwork and mileage, he fills it out and sticks it on.