weird debris under radiator cap

Hi guys.. was out looking over the jeep more closely today and was trying to pinpoint the source of this white greasy residue that's all over the front of the engine/engine bay/hood. Upon further inspection it appeared as if it was coming around the radiator cap area. I took the cap off and there was this white-ish-yellow-and grey greasy residue stuck to the bottom of the cap and the inside of the radiator filler tube.. the coolant in the tank was great, not brand new green, but no hint of any white greasy residue or discoloration.



I've got a few pics...













I have no idea what it is it almost looks like it has fibers in it.., the truck doesn't overheat, and it doesn't smoke...



One thing that i can think of is that the hood liner is falling apart, i'm going to take it out this week when i start working on it (off work for the week), and the cap needs to be replaced as it barely holds pressure i assume... it is incredibly more loose than any other radiator cap i've dealt with... doesn't feel like it really clamps down at all. But i'm wondering if any of that hood liner material could have gotten into the radiator?.. it wouldn't suck it in would it? There's no material near the radiator cap, but there are little bits of hood liner material fibers all over the top of the engine.



anyway... i look forward to your assistance.. any help is appreciated, thanks!