McCaskill defended Obama, saying the reason Obama turned around was to answer a question of hers.
Obama also said he and Hillary exchanged friendly waves earlier.
"I was turning away because Claire [McCaskill] asked me a question, as Senator Kennedy was reaching for her [Clinton]," Obama said. "And senator Clinton and I have had very cordial relations on the floor and off the floor; I waved at her as we were coming into the Senate chamber before we walked over. I think there's a lot more tea leaf reading going on here than I think people are suggesting."
McCaskill was on the plane with Obama to back up his alibi, and she scolded the press for reading something into nothing.