Loud back clicking. Is this normal?

Ive had rounded shoulders for an number of years due to over develop pecs, I have undertaken gym work to stretch out my back muscles and pull the shoulders back. As a result i get back pain. Ive purchased a foam roller and have noticed each time I use it to stretch out my spine there is always a loud clicking sound (which weirdly is a great feeling). Im conscious this could potentially be causing some damage. Is this acceptable or could it be an indication of some other issue?
I wouldnt be too worried but it happens everytime.

Cheers in advance