I'm going to start out by saying even though this is grain it doesn't fit the defination of the challenge. Details: Create an image where image grain or "noise" is an integral part of the message of your photo.
With that defination graininess in the photo is what was needed not actual grain.
Now as for the photo itself its an excellent macro with with good lighting and dof. THere is a small area though on the right side that appears slightly over exposed. The white is just too bright there.
Nice photo and remember even though you shot grain it doesn't always mean grain...=o)
This will open some discussion. The challenge called for the use of image grain - would have been a nice double-hit if you had added some noise to the shot but I really can't see any. Your image will be voted both ways I think as this is a great shot but does not meet requirements.