Nah i think it's a valid thing to be upset about, i remember seeing a few of my much-older graphics on websites, one particular charmer had taken a graphic that had my name on the corner, editted out my name and then turned the graphic into an award they gave out at their site - without ANY credit to me! LOL

Of course, as you also said, sometimes it's hard to know where a graphic came from but when you are taking them from websites directly, it's not hard to know where they are from! :X LOL