A Malaysia Airlines Boeing 777-200, registration 9M-MRH performing flight MH-70 from Kuala Lumpur (Malaysia) to Tokyo Narita (Japan), was climbing out of Kuala Lumpur when the crew requested to stop the climb at FL210* due to a technical problem and to enter a holding.
The report goes on to say that the crew subsequently requested a return to KL without giving further details.
They also didn't request any priority or assistance, which obviously indicates that it wasn't a critical emergency.
They then returned to KL for a safe landing about 40 minutes after departure.
The passengers were transferred over to a replacement Boeing 777-200 registration 9M-MRE and eventually reached Tokyo with a delay of 2.5 hours.
The troubled aircraft was then able to resume service 13 hours after landing and the DCA reported that the aircraft could not maintain the needed cabin pressure.
I don't know if everyone is being overly sensitive about any incidence occurring on a Malaysia Airlines flight, but there is an extraordinary amount of reporting on MAS (including that by yours truly).
*21,000 feet above sea level