2018 x30D Engine/Exhaust sound - slightly deeper ?

[Geo41e]

Hi guys

been wondering what is causing this "sound" difference for awhile now.

So once in awhile, no way to manipulate, my induction/engine/exhaust note would change, to a deeper sound. Nothing crazy, but noticeable to the point where i actually like it. Sound more aggressive. Again, nothing crazy but noticeable.

Most recently, it happened even below operating temps, and other temps at normal temps..again, very random. I was think it was triggered by the DPF burn cycle ? though as stated, happened below operating temps as well.

Also, no power loss at all, no vibration or smoke..just..sound

So, questions i have is,
Does the 30D have an exhaust flap ? (Note - sound happens in both comfort and sport modes)
anybody else experienced this ?

thanks guys !