Andy Pettitte’s back issues may have raised some eyebrows, but Yankees general manager Brian Cashman insisted he is not worried about the 40-year-old.

An MRI exam on Pettitte revealed nothing more serious than back spasms, according to Cashman.

“They did an MRI on it a few days ago to be certain it’s not an issue,’’ Cashman said yesterday. “There’s nothing there but a spasm, and that’s already gone.”

Pettitte is expected to throw a bullpen session today in preparation for a start in Toronto on Friday.

And if the test results weren’t enough to convince Cashman the lefty was OK, his own eyes confirmed it.

“I live in the trainer’s room, so I’ve been down on the table next to Andy a lot and I know he feels great,” said Cashman, who is still rehabbing a broken right leg from his skydiving mishap last month. “He just had a muscle spasm. That’s all it was.”

***Curtis Granderson spoke to students at Lincoln High School in Coney Island yesterday about the importance of Jackie Robinson before taking them to a screening of “42.”

“I wanted some kids to see it in Brooklyn,” said Granderson, whose Grand Kids Foundation also donated sports equipment to the school that was impacted by Hurricane Sandy.

Granderson said he started wearing his uniform pants legs up after seeing pictures of Robinson doing the same thing.

The center fielder is scheduled to start his rehab of his broken right forearm in Tampa today and said he is not upset about having to deal with the injury during the season leading up to his free agency.

“As long as I continue to play and stay healthy at the end of the season ... everything will take care of itself,” Granderson said.

***Francisco Cervelli is off to a surprisingly fast start, but that does not mean he has any better idea of whether he’s starting from one day to the next.