And I thought they wanted you to stay over on Saturday night

Earlier this evening, I booked a round-trip flight, on American Airlines, from Baton Rouge to DFW for my grandmother. It’s for the first weekend in August, to celebrate my son’s birthday.
Initially, I was looking at mid-morning flights out of Baton Rouge on Saturday, August 5th, and a mid-afternoon return flight from DFW on Tuesday, August 8th. I found great times for each, but the total ticket, even with a supposed senior discount, was $361, after applicable taxes and fees.
I changed the flight out of Baton Rouge to Friday, August 4th, same time of the day, and the price dropped to $260.
So apparently the new savings comes in with the Friday stay-over…