Today I was at the hangar and heard noise coming from the hangar behind me so I went to investigate. It was a hangar I'd never seen open with two older gentlemen getting an experimental ready to fly. I forgot the name of it but is was a high wing, open cockpit, fabric covered, tandom seating airplane which looked sort of like a Piper cub. He told me the name which started with a name similar to Baker. I couldn't find it online. Anyway the younger of the two (both over 60 maybe closer to 70) said that he had just sold it to the older guy who was about to fly it to Kansas. I noticed the new owner was getting up there in age and that his arm was shaking like someone with Parkinson's disease. Red flag goes up in my head but who am I to ask if someone has a current medical? I could tell they were busy so I excused myself and walked back to my hangar. I got my hand held radio out just to see what this guy sounded like. It was as if he was a student or just slow with bad comprehension. Ground had to ask a few times for read-backs and when he did it was "close enough". I switched over to tower's frequency to listen and he was very slow about reading back his clearance which the controllers slowed way down and enunciated every word. Soon after the clearance, the siren went off. I guess the tower's crash phone is connected to it in some way because every time there is an emergency, that siren goes off. The tower said to another aircraft that the runway was closed and someone had ground looped on the runway. I also heard the older pilot talking on the radio saying that he was alright and that there was nobody else on board. Meanwhile, the guy that sold him the plane was in his truck trying to watch the take off and when it didn't happen, he drove over to my hangar and I told him what I'd heard over the radio. He then told me that he had lost his medical and therefore couldn't take the buyer up for a flight in that plane. He also told me that the buyer admitted that he'd never flown that type before. The seller also told me that he didn't question the buyer as he said that he'd been flying for 30 years. His "mishap" as ATC called it, shut down the main runway for over an hour. I don't know why. If he'd simply ground looped it, they could have pushed the plane off the runway. It sounds much more serious than a simple ground loop. It was none of my business so I didn't say anything, but I still feel bad. I'd have felt worse had the old guy been hurt or killed.