Saddle marks?

[Hormonal Filly]

My horse is a grey, and on her back, the hair ok both sides (about the side of a fist) where the back of the saddle sits has turned brown?
Saddle has recently been fitted, and I have just got a brand new one which is a perfect fit by a master saddler... So it's cant be from any of the saddles I've had on her?! Or is it?

Could it be previous owners having incorrect saddles? Or
It's unseen in winter.. And whatever stain remover I use if just don't budge!
Any ideas?

 

[Dot2dot]

My horse is a grey, and on her back, the hair ok both sides (about the side of a fist) where the back of the saddle sits has turned brown?
Saddle has recently been fitted, and I have just got a brand new one which is a perfect fit by a master saddler... So it's cant be from any of the saddles I've had on her?! Or is it?

Could it be previous owners having incorrect saddles? Or
It's unseen in winter.. And whatever stain remover I use if just don't budge!
Any ideas?

If you wear white breeches with new leather chaps/gaiters you tend to get black marks. It's a similar kind of thing. Dye from the leather.