Coach Pep Guardiola was furious on Saturday, ahead of his side's 3-0 win over Borussia Dortmund, to discover that somebody had been leaking news from within the dressing room to German daily newspaper Bild.
He has threatened to throw out the culprit when he is found, but Lahm, while admitting his frustration, is not overly concerned.
"It's certainly uncomfortable, you've got to say," he told the city's Tz newspaper. "It's unnecessary and has nothing to do with fair play, but there have been things like this within clubs for 50 years."
Germany captain Lahm expects club bosses to "sit down and hold talks" but not launch a man-hunt or in-depth investigation.
"They're not going to go looking for him," Lahm said. "Hopefully whoever it is will now stop what they are doing."