We made the roux for gravy in advance, but it separated while in the fridge. Is this bad? or should we just proceed as usual?

my default fix for any/all gravy travails is my stick blender. blended gravy will not stay blended forever and will re-separate once it cools over night in the fridge. but it stays emulsified long enough to serve and eat :)

Easy fix: melt butter and flour and whisk it under

Once your roux has separated, it doesn't have the same thickening and stabilizing effect. Unfortunately, I would advise making a little more roux for your gravy. Maybe others have some ideas on how to rescue a separated roux.

it's probably fine...i would heat it and mix it up before making the actual gravy. once its all reincorporated you should be good to go!!