Classic scam with quick-change oil places.
Oh, you didn't come to us last time? Well just look at your filter, it's full of sludge (that we put there when you weren't looking and is actually axle grease). You need to pay us MORE to "flush" your engine (this is typically a horrible idea) and next time you better come to us so that "other" guy doesn't screw you again!
was my first thought actually.
I've seen a few things in the last couple of years, my sister-in-law actually drove home once with and empty crank case a couple of years ago when they didn't even put the drain plug back in.
Had something happen about the same time at another place, the wife took one of our Jeeps in to have something done and had the oil changed then.
The guy changing the oil knocked the sensor off the block, I looked at the engine after it got hot and she had AAA tow it home.
I was so pissed off at the time I actually walked to the place, the mechanic that did the work walked into the the office, took one look at me when I put one of my aerospace golf shirts on and waqs pretty pissed, and ran straight back into the garage.
The owner said I'll pay for it myself to fix it, he wanted to charge me for the repair at first when the wife called, I told her not to.
They had all ready charged her for another thing the week before, at that point they were just trying to hit her up for money.
Needless to say, have never taken a car there again.