I had an Alpine Type R 12" 12d4 for about a month sounded great. A few weeks ago my box slide all the way to the front of my trunk and was hitting my trunk latch. Didn't think anything of it just moved it away from the latch and got back in the car. Now I'm noticed some flapping noise. I don't know if it was from the latch or if something went wrong but the type r is in a sealed box and air tight. Also I can't hear the flapping noise in the car or outside the car only time I can actually hear it is when I open my trunk and stand back there. It sounds like something is vibrating on the left side of the sub. Anyone know what this could be? Unglued? Blown? Idk help??