but people on the spectrum often have these traits without being aware of them.
Yes - how many people have gone for diagnosis and "failed" to get diagnosed because of questions like these? FINALLY in the DSM-V they are saying that adults may have learned to mask their traits - This is a step in the right direction but what you said above is, I think, more often the case.
It was for me - If I had gone into my testing right after I discovered and knew I was on the spectrum, I probably would have failed the diagnosis.. I went in after a month.. and that was too early... If they would have asked me if I had any perseverations, or stims, or echologia or echolalia - I would have almost laughed at them and said "Heck No!" - But guess what.... Yes to all the above and then some.. and the list is growing still.