My friend's girlfriend is very immature. am i to blame for this?

i was hanging out with my homeboy at his place the other day. he lives with his girlfriend and their son. his girl was at work at that time. i was just having a lil smoke as we were playing ps3. my man's son was with us too. he's like 5 months now. his girlfriend came in, saw me smoking and was on me to like a *****. i mean whats so wrong about smoking in front of a baby? i know about second hand smoking but this is ridiculous. it was not like i was breathing down the kid's face. he was on the other side of the couch and i was just smoking a ciggarette, not snorting cocaine or something like that. don't you think that this girl overreacted? i had to put it out because it was their house but don't you think i wasn't to blame? i mean if the kid's father is cool with me smoking in his presence, why can't the baby's mother just mind her business too. btw they are both 17 and are young parents. i think that this girl is very immature and needs to concentrate more on being a good mother instead worrying about other people's smoking habits. i am right and she was just immature and overreacted.....isn't that right....who agrees?