Appreciate the kitz's comments were addressing plexy's situation, but by complete co-incidence, the day after plexy's return of G.INP, mine did the same.
There appeared no stimulation for this (ES were behaving quite normally - no sudden bursts for DLM to get interested in ) so it looks like, in my case, "that If the line is stable for 'x' period of time, then the DLM tends to apply G.INP." would appear to be the cause.
It took just over 9 weeks in my case.