Adrian Beltre and Elvis Andrus have a history of messing with each other, especially on infield pop-ups. The latest event in this saga occurred on Tuesday, when Andrus decided to draw a literal line in the sand past which Beltre should never cross.
Beltre wasn't that close to Andrus, just sort of mimicking his movements in front of him, but we understand Andrus' apprehension. Beltre has killed on collisions before, as Jacoby Ellsbury can tell you.