The Mecha ran back to the Cutter on autopilot, instructed to tuck itself back into the repair and reloading rack to wait for Max to call it again. The effect on the enemy was instantaneous. They began to move as soon as the Mecha was out of visual range, and the communications picked up the moment that it entered the Cutter.
They must have assumed that he was retreating to sleep and would be out of commission by the time that their movements were noticed because they weren't being subtle, and the drone feed was giving Max a clear picture of their current numbers and movement strategy.
There were definitely too many of them, and they were coming from near the signal that he had picked up, but that wasn't the only location. The data analysis from the ship indicated that there were six more likely positions in the region where they would have been appearing in larger numbers than would reasonably be expected given their losses.