This is how the Gorilla Glue dries!  See the way it foams up?  It sands off nicely though.
One important note though...  They recommend scraping it off with a wood chisel.  I don't!  I found that unless you are EXTREMELY careful the mahogany tends to give up slivers to the glue and you are left trying to fill or repair the holes.
I recommend a belt sander to take the glue down and then when it is nearly gone, a palm sander or even hand handing.
Belt sanders are too agressive for mahogany, in my opinion...

Another interesting thing about this picture that I had not noticed before... Look at the color of the windsheild frame behind the seat parts!  Much redder than the other pieces isnt it?  It tends not to look that red in person I think because of light and the fact that the surface is worn but everything points to a much darker red that I had originall anticipated!