How does one go about telling a colleague that they're using the wrong slide as a tuning slide? In my new (3rd section) band one of the bass players who I sit with is always sharp. Over a few weeks I noticed that whenever we're tuning she claims her slide is all the way out but she's still sharp. At the last rehearsal I watched what she was doing and she's using the 4th valve slide instead, while the tuning slide is all the way in. I'm a bit concerned about just saying something because I'm new to the band and I think she feels threatened with me being there. What's the best approach to take?