I personally feel that it is NOT off topic if the next reply is in connection with the reply they are responding to.... we can always get back to the original topic.
And - I personally like to see where the first question or topic might lead to - just like in real life.... one topic can start another one, but does that make it wrong - NO (imho).

BTW - I personally do not care if one of my post go to another topic while talking of the first topic... for that my dear fiends is real COMMUNICATION!!

LoVe,
Rhapsody - ((( hugs )))