"Carlos Zambrano said late during the 2009 season that he would retire if he had the same kind of season again.

"Look, this is the only season I haven't won 16 or 18 or 14 games," he told the Tribune. "If it happens again next season, two seasons in a row, I'll quit. Believe me, I'll quit. I just have to put this behind me."

No one expected Zambrano to quit in two seasons, not with millions of dollars on the table.

But Zambrano walked out on his team after Friday night's 10-4 loss and told some friends he was "retiring," and now the Cubs are wondering if he actually will carry through with his threat.

"It's shocking," catcher Geovany Soto said.

Zambrano's agent, Barry Praver, did not return phone calls.

Soto said there were no indications before the game that anything was wrong with Zambrano.

"We went through all our routines and he seemed pretty normal today," he said.

Soto didn't talk to Zambrano after the game, and wouldn't comment on whether he thought Zambrano would be accepted back if he returned. Marlon Byrd said he has seen it before."