First, my sincere apologies for taking so long to get back to you.
I'm afraid we're talking about two different Henry Pettits. Mine lived in the Philadelphia area his whole life and was born in the 1840s and lived into the 20th century. His grandfather was Charles Pettit, also of Philadelphia, who was a member of the Continental Congress and patriot.
My ancestors, as yours, were Huguenots who fled France. Mine settled in the area of New Rochelle, NY. I believe another contingent of Pettits (also spelled Petit and Petyt) settled in the South.
Sorry I can't be of more aid here, but I wish you the very best.