Eh, everyone gets that rule. Same with don't accept presents from strange bearded men, yet we get told the opposite at Christmas with Mr. Claus and his sack of presents.
Yep, glad to know you noticed. I can't wait until you see episode 9, I felt so regretful for him! His fault :P It seems like a normal episode but the end is just wow. Anyway, enough spoilers I think xD Tell me when you see it!
It happens quite a lot now, especially during the Red John episodes. I think iit is emerging more now as in the first 2 seasons, he was cheerful and tricked people, yet I think that he was quite stubborn too, yet would flex his ideas. However, the Red John happenings made him realise that he needs to be relentless sometimes.