as far as offending people goes...
i think mostly people will tell you if you have done something to offend them. and mostly people are pretty good about realising that it was unintentional. at least... they are once you say 'i'm sorry that you feel offended i didn't mean to offend you'. so long as you didn't mean to offend them of course... but i don't get the impression you are going around trying to offend people ;-)

sometimes there are misunderstandings. typically they are sorted out... sometimes it can take a bit longer... please don't let the odd thing put you off... you get them everywhere online and IRL. gives us good practice with dealing with those kinds of things IMO

:0)