Brown precipitate in spirit

[rectifier]

On my latest rum run (double distilled) I've let the first distillation sit around for awhile because I was too lazy to distill it again.

I noticed when it was fresh out of the still it was slightly brown colored and figured this was because I let it run quite heavily into the tails... but now, several days later, a brown ppt has settled out in clumps leaving the solution clear.

Now this is probably copper something, but usually people get a blue copper hydroxide, from a basic wash, don't they?