Does reheating a roux based sauce thin it out? I made a sauce that was thickened with a roux, and refrigerated it to be used again for another day.  When I reheated the sauce it seemed to be thinner than it was previously.  I added more roux to the sauce but that made it too thick, so I needed to add more base.

Was this all in my head and it probably wasn't any thinner or is there a reason this happened?
I would think that if there were a change, that the sauce would be thicker, due to water vaporizing and the fridge that tend to dry things out.

So, I think it's in your head, but of course I could be wrong.

The one reason why it might appeared so, is because the sauce will become thinner if you reheat it, compared to the consistency it had when it was in the fridge or at room temperature.