hello again!
thanks for all the great replies. I haven't flown in almost a week and the pain is almost entirely gone.
From what you guys said, I think it must have been due to:
-I am tall and the wrist stays at an odd angle in the C150.
-I am currently in Tahiti. Like in most tropical locales, it is not uncommon to have wind gusting at 20 or 25kts on final. This sure led me to grip quite a bit; I was on a new plane that felt very light.
Yes, it did hurt on the bone but also near the thumb. Maybe the former was caused by the grip and the latter by the wrist angle. I asked about the engine. It is indeed normal to have to adjust power every time the wind changes. This happens frequently on the Tahiti airport circuit due to the fact the island is mountainous.
I'll fly again on the C150 and properly trim and only use my fingertips. I'll make sure the seat is pushed all the way back. Also, by now, I know when power is about to need adjustment. This will allow to also use my right hand. If the pain comes back, I'll ask to switch to the 172....I will soon for navigation lessons anyway.
Thanks again!