It's time to change my expansion tank. There is a metal sleeve inside the nipple, but evidently that doesn't stop someone from cracking the plastic around it when they torque the hose clamp screw down.
Parts.com had the best price on the coolant tank at $104.40, as opposed to $131.16 from autohausaz. I ordered the coolant sensor O-ring and snap ring just to be on the safe side.
This is definitely the Achilles' Heel of the expansion tank -- Kind of like the 90 degree elbow on the radiator. It's just a matter of time before it cracks.
At least the white tank will freshen up the inside of the engine bay.