iPhone 6s - Silent Mode Cycles On/Off Independent Of Switch

Everything else on my phones works fine. But I can be just holding the phone and the Sient Mode notifications appear without me touching the switch on the side. Sometimes it will not do this but more often it does with the On and Off notications cycling through one after the other.

My silent mode switch on the side of the phone is clean and has a very crisp and definite on/off movement. The noticiations work properly when I move the switch.

I have tried to find a spot on the phone which, when touched, cause the notifactions to appear. But it does not work like that, the notifications can automatically appear with the phone sat on my desk.

Thinking this might be software rather than gardware related?