A’s pitching guru Rick Peterson may not be allowed to break his contract and join the Mets without bringing along some baggage from Oakland: disgruntled outfielder Terrence Long.

Long, who blasted first-year A’s manager Ken Macha after a dismal season and is mulling whether to ask the A’s for a trade, may be a stumbling block as the clubs negotiate compensation for Peterson, baseball sources told The Post.

On Wednesday, Peterson interviewed informally with the Mets, who were unsure whether Oakland GM Billy Beane would release the New Jersey resident from his contract without major haggling.

In other news, Houston GM Gerry Hunsicker signed a one-year extension with the Astros and ended his candidacy for the Mets’ GM opening.