a question of tuning

so as to avoid being off topic on another thread :O) I have a question I will pose here, I have noticed with more than one guitar that left to it's own devices and without any noticeable change ( though I haven't been monitoring this scientifically) in temperature or humidity etc. when checked with a tuner has gone sharp rather than flat. Any idea why this would be ?

My tele usually does this also. Before the start of every session I have to either stretch the strings or slacken off tuning a bit and then up to pitch. It stays in tune throughout the session from then on but once it's been in its case for a few days, it's sharp again!

The only thing I can think of that might cause this is if the strings are binding at the nut, as you tune up to pitch, the tension between nut and tuner is greater than between nut and bridge. Over time this will even out, causing the guitar to go sharp?

Others may have better ideas/explanations!

Oh no it hasn't.... and that's gospel!

Well, my take on it FWIW, is that *maybe* the guitar is resting in the case's neck support and the tension is reduced, so the tension behind the bridge and nut *could* take this up. So, when you remove the guitar from the case, it causes the playable string area to re-introduce its tension - causing it to sound sharp for a while, until the strings slip at the bridge and nut.

????? - I'm not much of a machanical kinda guy.

would be ?

I know this one!!! The world has slowed down since you last checked you guitar, so reference A is now flatter than it was, but guitars don't respond to the world slowing, because it's not rock'n'roll and they are forever young, so they seem now to be slightly sharp.