Little bit of yellowing

This is my first grow so I seem to worry about every little thing I see. I'm four weeks in and had been using T12 till yesterday when I went to a 400 watt MH. When I got home yesterday my kids where wilted and some of the new growth was somewhat yellow in color. Here my setup - One 400 watt MH with a Future-Brite Ballast and a Cool Junior Reflector. My grow space is 4 X 2.5 X 7.5 room is at about 78F will be putting in a Hurricane inline fan this weekend to try to bring the room down to about 73 to 75F. If anyone can tell me what they think about the yellowing I will be very grateful. Note In these pic’s I had just watered them because I thought the new light might be the problem and they needed the water they did look better and few hours later but the yellowing is what has me worrying.

Okay, at first I thought you were crazy, I didn't see any yellow leaves. Are you talking about your new growth? Fresh growth tends to be lighter colored, gets darker as it matures. No worries, your plants aren't yellow. In fact they look very healthy, nice growing!

Awesome thank you for getting back to me, just worried about my kids thought the light might be the problem.