I had a run in with this man about a month ago. The mention of the grandma reminded me of it! I was walking down M st. and he followed me for several blocks. He wasn’t aggressive towards me but I could not get him to stop walking alongside me. Luckily it was broad daylight and a very kind individual diverted his attention away from me and I picked up my speed and got away from the situation. A scary position to be in, glad you were also able to get away safely.