I got a brand new Brooks saddle a couple of weeks ago. Rode it 3 times (about 5-10 miles each time) with no problems until the fourth ride of 25 miles - and now it looks like it has worn down one side. The other side is fine and I have polished the underside of the saddle with proofide twice before this ride. Is this part of the breaking in process? Or is the leather faulty and should I send it back?