Xcode stops running when I don't watch it for a while. What's wrong? I am (trying to be) running Xcode 4.3.2. on Lion 10.7.3

I noticed that when I stop watching Xcode and walk away from the computer for a while (like half an hour or so), Xcode in the mean time stopped running and has to be started again.

I read a lot about Xcode on Lion being unstable. Is that what is happening to me? Is it that unstable?
This may be the built in "undocumented" to non-developers feature of Lion called Automatic Termination that is causing Xcode to quit when you don't want it to.

As noted in "Lion Is a Quitter"


  Lion will quit your running applications behind your back if it decides it needs the resources, and if you don’t appear to be using them. The heuristic for determining whether an application is “in use” is very conservative: it must not be the active application, it must have no visible, non-minimized windows — and, of course, it must explicitly support Automatic Termination.