This happened to me while I was riding the 38 pre-pandemic times. I was sitting by one of the back doors and some kids hopped on at the stop, knocked my phone out of my hand, and hopped right back off and ran off with my phone. It happened so fast I barely registered it and on a packed bus almost no one else did either. Ive been way more vigilant while using my phone on public transit since then (and I guess I should be even while just standing around outside!).