Yeah, it can get awkward when someone assumes you're going to push through when you were just trying to poke, but it happens. Same deal with friendly fire, people aren't always aware of exactly where their lines of fire are, and it can get messy with a bunch of big 'mechs packed into a tight firing line... but I like I said, shit happens. I don't even bother saying anything unless the same person tags me two or three times in a row. :/
I mean, that's half the reason why I make sure to set up a bunch of partial firing groups on 'mechs that aren't hill-humpers or corner peekers/have a set of hardpoints that covers a lot of surface area, it stops FF
and saves ammo/heat that would have been wasted on terrain. Not everyone bothers and TBH I don't blame them, it's an extra mile that you usually don't need.
It
does peeve me a bit though when someone FFs because they're trying to kill-secure when there are other enemies to shoot at (except lurms, because those poor bastards had no way of knowing that you'd be in the path of their missiles ten seconds after they fired). Not if it's genuine accidental from firing into a brawl, but if they just drag right across you trying for a clear angle. Sky/ground-flick your lasers when you tag friendlies, fuckers.