HKG,
I wonder if you just got a cranky agent who was trying her best to derail your travel. It seems she succeeded in doing so by having your bag arrive so much later than you. Seems that the whole interaction was designed to get your bag separated from you and thereby inconvenience you. I have found a few agents who overreact when they are pressed by a passenger to hurry up to accommodate them. It has happened to me twice.

I travel with my daughter and we usually arrive at the gate with a rolling bag that holds my laptop and a few other personal items, on its handle hangs my daughter's backpack full of toys and a lunchbox full of my daughter's food, I carry my purse and usually a shopping bag to hold our coats, gloves, hats, etc. Sometimes you can add to that a Burger King bag and a couple of sodas. Oh, and my daughter is usually carrying some kind of stuffed animal. Lots of stuff. Did I mention the gate-checked stroller? They have never questioned my carry-on circus. But they did make me check my daughter's baby fork in a 16x16x16 box once.

Sounds to me like you were punked!