I've often thought my corydoras were stuck in my bogwood, seeing as they'd stay in there, in the same position, for hours at a time. But when moving the wood out of the water, they'd swim out. I recommend you try removing the wood out of the water first (not far out of the water, nor long!).
The pressure difference between the water and air often causes them to actually be able to get out anyway. If still no success, I guess you'd be best off trying to wriggle him out (carefully ofcourse) with your fingers.
Good luck.
[snapback]918678[/snapback]