Okay, an update... I was wrong about the pano roof with the 3M Silicone spray. it has returned in full force. probably just disappeared for a couple days due to the warm weather those days.
it's more like a tic or a sticky sound. kind of like when you get a piece of gum stuck on the bottom of your shoe and when you lift your foot off a hardwood floor, it makes a "tic" sound. Or when you walk on a sticky movie theater floor. can't wait for it to get fixed. it happens on damn near every seam in the pavement. incidentally, i did not have this at all until two weekends ago, when i visited someone who lives on a dirt road. i think the increased flexing the car experienced on these rough roads loosened something.
The silicone spray didn't work on the seatbelt rattle either, but for a different reason. I FINALLY found the source of the seatbelt rattle. and it's NOT the tensioner or any mechanical part. Ready for this? The sound comes from the friction between the seat belt itself, and the piece of biege plastic that surrounds (covers) the seatbelt intake/tensioner. Basically, they are both dry, porous surfaces that tend to lightly "catch" when still. then, when your body moves ever so slightly and pulls (or pushes) that seatbelt against the plastic, it makes a very audible sound that sounds like a rattle. made worse by the fact that it's next to your ear.
so we need to come up with something to put over that piece of plastic, where the seatbelt rubs as it comes out of the opening. maybe some kind of smooth tape. will be hard to get it to look good. Tonight I am going to try a simple piece of scotch tape.
I will report back. sorry for crying wolf before. i will be more cautious from now on in reporting findings.
p.s. - this seat belt issue reminds me of maybe the only design/feature part of the car I do not like... the fact that the seat belt height is not adjustable. WTF?!?! Honda Civics have adjustable height seat belts! I'm 6'1", and i swear the edge of the seatbelt rests RIGHT on my carotid artery on my neck. very irritating. if I could lower it, not only would it not rub my neck raw, but I don't think it would rattle either as the belt would extend OUT and not touch the plastic covering, instead of currently where it extends DOWN and rubs both the plastic, and my neck.