First a clarification. You are not addressing Adobe here. These are user-to-user forums, not a channel to communicate with Adobe.
We are all users just like you. Some Adobe staff do contribute sporadically on their own time and dime, as volunteers; but Adobe does not officially monitor these forums.
So, don't expect an official response from Adobe.
That being said, the "bar" problem you mention could well be an issue with the video card in your Mac Book laptop. I cannot replicate your problem on a Mac Pro desktop tower, running Photoshop 13.0.5 ("CS6") under Lion 10.7.5.
Intel Xeon Mac_Pro1,1 2.66 GHz Quad; 16 GB RAM; mutant/flashed, factory-overclocked ATI Radeon HD 5770 with 1 GB of VRAM; Mac OS X Lion 10.7.5.
Perhaps if you tell us what specific steps you take in Liquify, some other user who is running Photoshop under Snow Leopard 10.6.8 can tell us if he/she can reproduce the problem. As I said, I'm not seeing this in on my system.
Of course, please do make sure your copy of Photoshop is fully updated to version 13.0.5, which is the current version for the Mac.
JJMack beat me to it, in a succinct manner.
I have not seen or heard of this problem before. That being said, I would try upgrading to a newer version of Mac OSX. (this gets you a video driver upgrade as well) Apple has fixed a number of OpenGL bugs that might contribute to this type of problem.