Hello,
Based on the output you attached, it looks like the memory issue is related to VPN functionality. The 7.2(2) PIX code is a bit old, and there are a handful of bugs that affect memory utilization when VPN is used.
I would suggest an upgrade to at least the latest 7.2(4) image to get the fix for these bugs. If you need more details on specifically which bug is causing this issue, please open a TAC case so it can be investigated further.
Hope that helps.
-Mike