Help FAST! Short light cycle interruption... adjust cycle or leave it??!

I forgot to close the curtain on my grow room. The HID lights went out at the normal time, but they were still receiving indirect incandescent light for 20 mins. I realized I left the door open and shut it within 20 minutes.

So, it was at the end of their light cycle. Should I let them stay on their regular schedule and only get 11 hrs 40 minutes of complete darkness, OR should I move my schedule back 20 minutes? This way they receive a full 12 hours of darkness, but it would shift their schedule slightly.

I'm wondering which would be less stressful on the plants. I can't have any hermies, they are on day 46!!! What do you think?