change in hydrometer reading

[zaph1]

Following 1 week in medium toast, finely shaved oak chips, my brandy dropped from 155 proof down to 125 proof. The chips were previously used to run 90 proof whiskey and were still a wet since I had just pulled the whiskey from them. I made sure to tightly secure the lid on the jar so it's not the "angel's share". Even if it was the "angel's share", I didn't think it would be 15%. It can't be 15% without a significant change in volume and I started with and ended up with a full quart jar. Could something be imparted from the chips that would change the SG of the alcohol? When mixing it down, should I use the original 155 proof reading or the current 125 proof reading?