It looks like a flowering quince, something like Double Take Scarlet that is thornless, and can bloom in the fall. The next closest match would be Camellia, but I doubt they can grow in zone 6.

It is a flowering quince which may or may not have thorns. Some varieties do not.

from a web search :

Proven Winners Double Take Series of chaenomeles are thornless and have higher petal count. ... Recently a breeding team at North Carolina State has taken the thorns out of flowering quince. Called the Double Take Series, these new thornless varieties also offer doubled-flowers in dramatic red, pink and orange hues.Dec 27, 2010

Many shrubs may produce flowers in autumn due to weather changes. It's not unusual to see a few blossoms.

Yep. Chaenomeles, no question.