aims, reading your post, it could have been me writing this about my son. It sounds like your son is just finding his feet in Year 2. When they first start school it is new and a bit daunting to say the least. Some children like to see how far they can push he boundaries - unfortunately some teachers like to categorise children and mostly only like the submissive ones.
I had very similar problems with my son at that age, he did well in all his subjects, but did like to act the classroom clown, larking about in line and talking a lot in class. One teacher in particular, constantly called me in school to tell me about something or the other he had done. Children do pick up on if a teacher does not warm to them - teachers should be impartial and treat all pupils the same - I know from personal experience this is not the case. Your son may be picking this up from a teacher, so to try and please them, he feels the need to act different.
Them asking you if anything has changed at home - this is a classic teacher question - put the blame on the home life. I would also say, aims, be very careful what information you give teachers. It does not always stay confidential and can become the talk of the staff room.
I think your son sounds like a normal 6 year old little boy. Try not to worry (but we all do).
My son is 20 but it is still fresh in my mind how nasty and judgmental some teachers can be.
Love Denise xx