Odd problem when accelerating from a slowing down

I serviced the transmission this year (gasket, filter, the whole transmission service kit, 4 quarts plus a half a quart Mercon V I added myself after the service) and there are no warning lights on the dash. However, the transmission service did not replace all of the oil inside. Be it noted that the old oil in the transmission (when police were maintaining it) was red and clean. There is a little debris in the pan, and the tech also cleaned out the magnet. A note: I discovered that I was handling my transmission a little too gently fearful of damage, because even in the described "problem" above, at higher RPM's, if I were not to lift my foot of gas, and kept pressing at 2-3 1000 RPM's the car is still engaged in a gear, maybe it is still at that point in overdrive which is why the noise occurs, but the transmission is not disengaged in my example. What do you think?

The debris found in the pan was described by the tech as "little dirt, all normal".