Thanks everyone for the comments.
Poppy - I will say that the difference between my son's teacher and your relatives is that...she's his teacher! If she wants me to be consistant with her methods, she needs only ask. Remember, this is the woman who, when asked, "How was the rest of his day after the hard drop off?" answered, "We'll talk about it next week." If I'm undermining, then she needs to communicate better. And perhaps not wait a week to implement her ideas.
Let's be clear - I totally appreciate her efforts, but how on Earth am I supposed to know that I'm not allowed to pick up my son, whose tiny face is blotchy red and streaked with tears after a 30 minute battle with the "take a break" chair? I was totally on board with not going in and disrupting her during this whole fiasco, but I almost started to cry myself, because I was going to have to break a promise to him that I'd be there for library time.
And I must have miscommunicated to everyone my story about asking him if he took a break during the day. I certainly wasn't quizzing him about being good or bad. As a matter of fact, the first time we had the conversation, he was the one who said, "I had a good day, and I didn't take a break." Anyway - I'll be sure not to ask. Again - no one wants him to succeed more than I do. And I do think these people are "early learning experts". I know I certainly am not. I guess I just perferred his teacher from last year - she made me feel more like part of the team - not some no-nothing mother who is doing and saying the wrong thing. I'm pretty tough - I'll get over it. And I'm sure over the next 13 years I'll run into more good and bad teachers.