Ultra 4K HDR - Model 4802X - Ghost start ups while operating normally

We have been enjoying our upgrade to 4K and HDR along with improved sound... however one anomaly has surfaced and wondering if anyone else has had this...

1) While operating and watching streaming content - we have heard the initiation sound that begins when you log into a streaming service... usually quite loud and annoying?

2) Not sure if a shadow session is running in the background or such...

I have powered down and off completely a few times to ensure we don't have duplicates running... but wondered if anyone else has seen or heard this phenomenon.

Thanks in advance.