Wrong iPhone diagnostic test result from Apple support?

So recently I contacted Apple support online and they offered me to do a diagnostic test for my iPhone. My initial thought was there's something wrong with the speakers (because the bottom speaker area tend to get warm when in use), but the result showed that my bluetooth sensor is having a problem. But it fact my bluetooth works perfectly fine, and so does the wi-fi (I'm assuming that the bluetooth and wi-fi is in one card?). Could someone explain this? Should I ask for replacement regarding that my device still works fine? If that eventually they'll have to replace the bluetooth sensor, will they replace only the sensor, the logic board, or the whole device? Thank you!