"The flight, 5M 2109, from Antigua with seven passengers, landed normally and decelerated along the runway. The pilot thought that he felt a minor vibration and as a precaution, he let the aircraft roll gently onto the grass, where the passengers disembarked. There were no injuries and no damage to the aircraft."
Hard to see any reason to ground them based on the statement above. Mind you it has been an awfully long time since I last flew a BN2A.