Whoops, you got yourself a jehpeg. Photobucket auto saves BMPs as jehpegs so make sure to save as png or gif before uploading.
One thing I will say about grass tiles is that it's usually a bad idea to do a grass tile alone. Most of the time you end up having to rework the grass because it's too contrasty, detailed and lots of other things. It's a background graphic which is a fact that usually gets forgotten if you don't have some NPCs, trees or buildings to remind you. Doesn't look taht'll be a problem with this though can't be too sure because of the jehpeg. Post back soon