This may be a silly question but I noticed tonight when braking in my 2012 Clubman that the side turn singal would come on.this only happens sometimes. Does anyone else notice this.

 

The exterior bulb? Are you braking hard when it comes on?

 

Yes the side light on the fender and no not braking hard I've only noticed it a few times. Just thought it was strange .

 

The rear turn signal lights come on with the brake lights if you brake "hard" past some threshold. I saw that when following my wife home one night.
Maybe the side markers are wired in parallel? Is that how you are seeing exterior lights when driving?