Random T-Mobile Diagnostics message of "test"

tmo_stan wrote:

On March 7th, some Android users reported receiving a "test" message from T-Mobile Diagnostics. This message was delivered by accident and will not affect the device. We apologize for any inconvenience and, if you haven't already, feel free to dismiss the message.

It looks like there is more to this so called accidental "test". I did notice that when it happened my microphone indicator showed that my phone's microphone was turned on even though I didn't use any app that would require it. I had to restart my phone to get rid of the indicator, but I'm pretty sure whatever software triggered it now has full access to my device and can spy on us. Anything TMO can respond to the breach of our privacy?