Alvarez was removed from Thursday's Grapefruit League game against Houston due to back tightness, Max Goodman of NJ.com reports.
Alvarez struck out in the third inning in his only plate appearance and was replaced by a pinch hitter in the fourth. Mets manager Carlos Mendoza said the backstop's exit was precautionary, though it's not clear if Alvarez will miss additional time. He's been having a strong spring, slashing .364/.423/.636 with one home run, three doubles and four RBI through 10 games.