Dave .. you are fine ..
There is nothing inappropriate about the way you reply to posts ..
Hijacking is going way off the subject of the initially created thread - I have had to move posts to their own threads because they were totally off topic to the subject being discussed .. or new members introduce themselves in already made threads giving their post little exposure ..
They are usually individual judgement calls ..
I see nothing wrong with posting your experience or photos in threads. You are right, that's what the board is about ..
What made you think that you are doing something inappropriate?