Sabrina's right - there's no option for the owner of a photo to delete comments that are left in the gallery so the only options would be deleting your own coments (which presumably you'd know about!) and the moderators.
As with posts in the forum, I think the only circumstances where mods would delete something would be if it broke the SCS terms of service (basically you'd have to be really offensive or advertising/soliciting - the full site posting rules are
here).
Did you have the picture saved in your Favorites or did you go to it again through a search? I'm not sure what would happen under Sabrina's delete/upload again scenario if it was in your Faves - I'm imaginging the new upload would be in a new location so it would no longer be in your Faves list?