HELP !! Where would I find probate in 1826 for OAKLAND COUNTY ?

Michigan became a state in 1837.My ancestor, Rev. John Stewart, died in 1826 in Oakland County...just 4-months after moving from Seneca County, New York.

An article mentions he had a probate...but when I talk to folks at Oakland County courthouse, they say their probates start much later.(You might think they would have them as they were formed in 1819 from Wayne County.)

Might I find these papers (perhaps) in Wayne County, Michigan...Detroit ?Can anyone help find these who lives there ?

Thanks !

Steve