I never, ever check my phone whilst driving but I always get really paranoid if I look down at my lap whilst pulled up at a traffic light that people will think that's what I'm doing (I know I think that of everyone else who is looking down).
I have a bad habit of picking at my nails to keep them clean or if I can feel one is a bit jagged. Or I might look down to pick a bit off my trousers or something, I dunno, I just know I automatically feel really guilty if I lower my eyes whilst waiting in traffic. Nothing suspicious or exciting going on!
I know what you mean. I'm that forgetful that I need to make sure I've put my shoes on etc but yep I know what you mean re feeling guilty and might be construed otherwise.