Sorry guys, I missed this.
I'm on OSX 10.6.8.
No, it doesn't seem like there is a constant climb of system memory usage.
I'll be able to put this through some tests on my show machine tomorrow, which is on the same OS. (A Mac Pro that just delivered... I pulled Lion off and installed Snow Leopard 10.6.8)
If there is something specific I can test or look out for, this would be a good time.