I have had two OHS in four years and my chest never popped or crackled after either. Both my surgeries were open sternum.
No in the vast majority of my experience this is not the case. You should get a chest x-ray as one of the sternal wires may have broken early and not allowed the bones to fuse. Not much that can be done now. But you should see a physician because indolent infections can present this same way, and can also be reasons for re operation.