Power clicks and slide to unlock sounds lower?

[michael31986]

Noticeably randomly the phones slide to unlock and hitting power button to turn off screen sound gets very low. Not everyday and I first thought it was cause the battery was lower but it did it again before. A restart fixes it but weird thing is ringtones and text tones sound normal. So it must be a bug

 

[michael31986]

If u do Siri from lock screen the. Slide it. It is low for about 3 times. Wth