No worries really. All opinions, negative and positive, are welcome. It's manners (or the lack of them) we care about when moderating, not opinions.
As for your "responsibility" or to be accurate, the lack of it, as long as your posts are respectful of other people you got nothing to fear. It's obvious you started a thread in good intentions, it's not your fault it got slightly off-topic. Also, even off-topic tangents can have merit and threads are allowed to go on as a result.
I would also like to extend an offer to any user, if at any point they want help to maintain a thread they started on its intended track, they are welcome to post in their thread and request it. We now have enough moderators to cover all timezones and it wouldn't be a stretch to say that more than 95% of threads are actually being read by us.
If at any time you (or anyone else) wants some help maintaining a thread, you don't even have to PM us. Just post in your thread and request help. You might want a thread clean up, or just splitting off-topic parts to a separate thread. Just post in your thread and ask (reasonable stuff of course, ie, we won't do anything if someone tells us to "delete posts of people that don't agree with me" if those people post within the rules
)