Does this happen with a companion out? They feel like lines that extend to show the level of the character/companion. When I was messing around with a Jedi Knight and had that droid out I found to start seeing green lines when traversing hills, rocks, stairs, etc that came out at an angle similar to what the companion was at the time. Does seem like something common enough that someone would have bugged it in beta...then again the Mini-Jedi Master has not been fixed either.