No there's no sign of any cracking, just a hump which I didn't notice at first but we did a gig where the venue had a dancefloor that was lit from underneath, when my bass was lying down pre gig I saw it in the light. Now I know it's there I notice it more.
It hasn't got any worse in two and half years since I noticed it and I've wondered if all doublebasses have it to a degree, but as I said I've nothing to compare it to.
I don't get many issues with feedback and a tight soundpost could actually be helping this I suppose. My amplified sound is fine and I fear any improvement on acoustic sound, by having a proper setup, could give me more feedback when amplified due to a more resonant top.