meh.
First time I played polo I almost ran into a bystander and apologised, he was like "don't say sorry!! I'm standing on your field man!". and if you watch beginners mauy thai, you're more than likely to at some point hear a trainer shout "Don't say sorry!"
It's an action sport, which by default includes being shot with plastic bbs. Accidents will happen, you will get shot by mistake, deliberately etc. etc. althou, it's always nice to receive an apology, and to give one. But I'd say it's not to be expected in most cases.
oh, just as a side note! Once I ran into a room and started shooting the very startled occupants. Some 14 year old or so that didn't get out of the way fast enough when he was hit got a bit offended when a few more bbs hit him.. not deliberately shooting at a dead man thou (cramped area, many people, very fast action, people entering thru the same door he was using to leave, etc). So he thought it was a good idea to get into a really cool pose, probably saying something in line with "I'm already dead you moron", pull out his desert eagle, aka mighty fearsome deathbringer, and shoot me repeatedly in the stomach area at almost point blank.. I might even have felt it if he used a proper airsoft gun^^
(might just copypaste that to a battle stories thread sometime)