It's not suppose to. Acoustical caulk is supposed to stay pliable. Exactly how long ... don't know. A quick google came up with this:
Acoustical sealant has the capability to permanently retain its flexibility, allowing it to work effectively for a very long time. You can think of it as a non-hardening caulk.
I imaging you need to check with the manufacture of the product you're using to get a real number.
They use the word 'permanent' but in reality environmental conditions (low humidity) along with mechanical pressure (in this instance the constant movement of the clip up and down) could eventually sever the material. Unlikely?
Probably.
I just hate the what ifs.
Considering your project is as far along as it is, this is probably a solid solution. Going back to a design phase, these are some of the ideas a person ends up changing. Maybe you would have opted not to use metal channels now, or perhaps you would have found a rubber clip system, etc.
Funny how much you plan these out and can still come across changes you wish you could have made or thought of earlier.
Grab that sub and crank up some low frequency noise in the room and see if anything else rattles before you close it all up.
