This may sound silly but you have to take the MBP back to Apple Store.
Try Reset SMC .
Choose the method for
"Portable computers that have a battery you should not remove on your own".
You may be experiencing runaway applications which will load your CPU and cause temperatures to rise and speeding up the fans. Look at this link:
Next time this happens, identify the offending application. If it is one you can shut down, do so. A restart usually will cure the problem. If this persists, take a screen shot to use as diagnostic evidence for the genius bar technicians.