I definitely saw the same. It looked empty at kickoff, but 10 minutes later or so and for the rest of the game it looked full.
I got to my seat about a minute and half in. It's funny when I come straight from Connecticut I always get in early. I met up with my buddy in the City first yesterday (he lives in Brooklyn and sadly is a Cows fan) the 4 express didn't seem to be running because of some maintenance issues? Had to take the slow 4 along with a ton of other City supporters and a fair few Galaxy fans as well arrived at the crowded security gates just in time to get inside the stadium as it was kicking off.