I have a Gibson SG std that I tune to C# std. For some reason I have to tune the low C# a bit flat to get it to sound right. I have the intonation perfect on the guitar. I have tried everything on it. Bigger strings are no help. I have tried adjusting the saddle on the C# to make it flat even but nothing helps. I have other guitars that I tune to C# with the same strings and scale length and I dont have this problem. Is this just a normal thing or do I have a problem guitar?