Damn, your right. Never realised that.
Scale of the texture you say?... hmm...
Oh, and another useful tip I found! (Not too sure if it will fix your problem or not, but it helps). Create 2 or three lights where you need your light position to be. Offset them all from each other a little bit (depends on distance, gradient desired, etc). Then lower the brihtness of them all. This should give you a nice smooth light gradient. However, i'm not sure if each light has its own lightmap, or each texture.