PORT ST. LUCIE — GM Omar Minaya just announced to reporters that the Mets are sending Johan Santana back to New York for tests tomorrow on Santana’s sore left elbow, including an MRI exam. Minaya portrayed the long-anticipated move as nothing more than a precaution, but it still sounds ominous. Incredibly, the Mets still plan to let Santana throw a 30-35 “light” bullpen session here this morning. … 10:55 A.M. UPDATE: Santana just threw 31 pitches off the mound, going mostly with changeups but dialing up the velocity as he went along. He said he felt fine afterward, but how his elbow fares over the next 24 hours will obviously tell the true story.