I get this exact sensation - the cell phone vibration/buzzing feeling. I just went through a bad few weeks of anxiety after being great for almost a year and this happened to me in both my legs. It also came on near the tail end of the anxiety flair, I think when my body was starting to settle down. I've also found that it's one of the absolute most sensitive sensations when it comes to being psychosomatic. I'm 100% not messing with you when I say that as soon as I started typing to you about it, my left leg started to buzz even though I've not had the feeling in about a week now. It's amazing what the mind can do.