Mets officials were concerned enough about a blister on top pitching prospect Zack Wheeler’s middle finger that they recently sent him for an MRI exam on the affected area, a club source told The Post yesterday.

Assistant general manager John Ricco said he was unaware of the MRI exam, but confirmed Wheeler was bothered by a blister during his first two starts for Triple-A Las Vegas. Ricco said the blister, located under the nail on Wheeler’s right middle finger, burst during the right-hander’s appearance on Tuesday at Fresno.

Wheeler has dealt with a similar blister problem throughout his minor league career, last year missing a start for Double-A Binghamton because of it. The blister’s reemergence might explain Wheeler’s unspectacular start to the season: He is 0-1 with a 3.12 ERA in two starts with 11 hits allowed in 8 2/3 innings with six walks and nine strikeouts.