Not sure if it's relevant but over the past week I've found the freecount dropping down significantly less than it was before (whereas it would probably drop to <10 in just a few hours, it's now a day or two -- at critical my watchdog re-inits do my app never actually dies - as hacky workaround !). This is with a fresh sync from jcw's git repo about 1wk ago. [ my app does a web post every 5 seconds, ie around 17k / day .. so quite a lot]
It may be a co-incidence but I've spent a fair bit of time trying to reduce the RAM utilisation of my code - both by looking thoroughly at my app code (I've changed nothing in the libraries) and the build settings I'm using in Eclipse/AVR Plugin.
I had also wondered if the problem was proportional to the amount of received (/unhandled) network traffic - in previous weeks my home network was more busy and I also had a misconfigured router which meant a lot of unwanted broadcasts including duplicates were hitting the nanode board - maybe causing the issues.