I find in general that they are more lenient when it comes to little ones. I just boarded this week in Cape Liberty, and the person in my security line is someone I have encountered before. Let me just say that if I had the opportunity, I would smack the ^%$%^ out of her. She's a mean one, Ms. Grinch. She started to take away a small child's bottle of half-drunk chocolate milk, and mid-sentence, said, "Oh, go ahead, it 's fine", immediately after yelling at someone to throw out half a water bottle.
My daughter carried on three LARGE bottles (48 oz?) of Ripple for my granddaughter. No one even ASKED her what they were. (she wasn't in Ms. Grinch's line)