I was driving a 01 Sentra SE that would scare the hell out of me during emergency braking, so the SRT's brakes feel awsome compared to it. Had to do an emergency brake because of a dumb bitch in a bimmer and they worked AWSOME!!!!
Give it a few days, and if they still don't feel right get it to the dealer and have them check it out....that's your livleyhood during an emergency....
Oh, and mine doesn't feel "mushy" just not as firm as I wish.