Ymmv
I have been asked both times re-entered at US POEs (LAX and EWR). These were after 5 and 3 months of absences respectively, and I was asked the question even before they started scanning my GC/looked at the passport. At LAX the agent did not say anything further than 'welcome back'. During the second time at EWR, my wife was re-entering after ~8months. So we both got grilled a bit about our intentions to stay in the US. We told them we owned a house, had bank accounts, CCs, was coming back to jobs in the US and that seemed to satisfy the agent.
The only time I wasn't asked anything was at the US POE in Calgary, Cananda.
From my experiences with US border agents (both land and air) over ten years (as F1/H1/GC), the only thing you can reasonably expect at POEs is variability.
That said, if you are coming in after 9 months, probability is high that you will be asked some questions. Honesty is the best policy when questioned.