He probably doesn't have to tell Gabriel that, for some things, it was too late to protect him. Especially after the debacle with the last tablet. Instead, he squeezes Gabriel's hands and pulls his back.

"We were headed for Chattanooga," Sam says, reaching for his bottle. "At least, that's where the spell told us to go. Really weren't expecting to meet our quarry about half way." Even at Dean's driving speeds, he hadn't expected to reach the city until close to nightfall or just after.