Muffler baffle causing knock?

[grape of wrath]

I've been hunting this knock problem for awhile now. I went through the knock list and as I was checking the exhaust system I noticed when I punched the muffler there was a loud vibration coming from inside the muffler.
I'm quessing a baffle inside came lose and is causing the problem. I already ordered a new muffler. Do you think this would set off the knock sensor?
Anyone ever have this happen?