squeak/creak from rear seat DC

So, as the title says, there is a squeak or a creak (whatever you want to call it) coming from behind the rear seat of my DCSB. I have two tens behind the seat, but it just happened within the last week or two whereas I've had the subs for around 6 months. I've gone through and tightened down all the bolts, so I'm kind of at a loss here. I even so much as had someone sit in the back seat to try to find the sound. It almost sounds as if you are stepping on a loose floorboard in a house. Has anyone ever experienced this problem before or does anyone have any suggestions for fixing it?

 

Are you sure it's not the seat bottom? I had a creak coming from the rear seat bottoms about a month ago. I tried tightening all the screws down and it still squeaked...it went away by itself after a while.

 

I'll have to try that, it sounds like its coming from up top on the seats, but that's definitely something that I'll check.

 

Had this happen to me but in the front driver seat I retightned all the bolts and it finally went away was very annoying