I suppose it’s possible because i was doing volume readings with my sight glass which isn’t the most precise method but here is why I doubt that: my system has never had less than 1.3 gallons of boil off per hour and is usually around 1.5 gallons per hour. So even if I misread my first reading by 1/2 gallon (making it 8 gallons) that would only be a boil off of 0.75 gallons to get from 1.048 to 1.053. I know I lost more than a gallon to boil off.
I’m completely stumped. The grain bill was:
1.25 lbs C80
10oz roasted barley
1.048 is about 78% conversion efficiency which is around what i usually get so this number seems more believable. This just leaves the post boil measurement in doubt which was why i wondered if wort stratification was possible with an all grain brew. I didn’t think it was but I wanted to verify.