Subwoofer clicking noise

[gfspiderz]

Hey guys i have a single p3d412 and recently when i was checking out my truck i pushed in on the cone just to test it out. For some reason when I push a good way down it makes a clicking noise, is this normal or is the sub woofer blown? It sounds normal and such but idk if i should be worried.

info about my system

AMP alpine m-500

sub rockford fosgate p3d412