Ringer volume on Galaxy note4

Hello everyone,

I am new to this forum and new to the android, so looking forward to gain some insights and knowledge from all you here.

For the starters, here is my first query to all of you...

I am noticing a weird behavior/issue/feature on my note 4 since the Marshmallow update 6.0.1, let me break it down for you...it will be helpful if you guys can let me know if this is an issue or just a normal feature..

So when a call comes, the ringer initially rings at a lower volume before jumping to the user set ringer volume(for the purpose of discussion lets call this initial volume as 10% and the user set as 100%)
Now here is the issue/feature...so when I answer the call as soon as the phone rings and while its still ringing at 10% level...the phone automatically sets the ringer volume at 10% in the settings on its own. But if I wait a second or two, let the ringer reach 100% and then answer the call then its fine, no changes at all.

Please let me know if you guys also experience it and this is a normal feature or is this an issue with my phone ?