Question

What caused Thomas Jefferson to be grumpy?

Answer 1

Thomas jefferson was never really 'grumpy' in the aspect I think you were talking about, and his cause of death was actually unknown. If you have a more direct question or another question about him, please reply to this answer and I'll help you out. :)

Answer 2

The only thing I know for sure is he was I angry about the DNC tilting the Election  and he had a quiet opinion on slavery that affected the abolishment.