I crossed the border from Reynosa to Hidalgo-McAllen on Saturday.
I took the usual cab to the area where they inspect motorhomes, cars and travel trailers.
The agent at INM there said I didn't need an FMM anymore. He just stamped my passport and let me go.
Coming back to Mexico, I just stayed on the bus.
Has anyone else had a similar experience? Since I can't get a through bus to McAllen, it's kind of a pain to have to go to INM and return to the bus station.