K&N Aircharger questions

How's it guys and gals,
i recently installed a new intake on my 07 taco. The

$318 K&N 63-9025 K&N Cold Air Intake System: High-Flow Air Filter, Increase Performance & Towing: Compatible with 2005-2011 TOYOTA: Tacoma, 63-9025

K&N 63-9025 air charger kit. So far I have a little over 50 miles after installing. i am pretty satisfied with the little power boost it gives me and I dig the engine sound when I put my foot down. One thing I only noticed this morning is that when I start and kill the engine there is some engine rumble, similar to that which would be norm on a diesel truck. Everything seemed to be held in place pretty well when I tried wiggling stuff after the install, so I dont think anything is loose. Just wondering if this is the norm with this kind of intake or if i should be looking for something. My one thought is that it may be coming from the intake tube moving with the engine while the heat shield sits still on top of the wheel well. When i installed the heat shield i had about 6 inches of extra rubber molding that was hanging off one end, so i cut it to fit and have the extra still, thought it wold be an easy fix if i ended up needing it. i'll probably put that extra molding in the slot of the heat shield where the intake tube goes through, should only help right?

Thanks for reading and any thought or comments!