Good morning Ed.....

The spots are most likely from too much heat and humidity. My tomato starts and peppers have the same. Once I turned off the heat matt and let the lights be the heat source, those leaves fell off and new ones do not have the spotting. 

Thank you for this clear answer. Is any added nutrient appropriate at this point? Or should I just start repotting the bigger ones into the intermediate quart-size containers prior to planting in the main outdoor garden?

Hi Edn

I wouldn't add anything at this point but if you have an extra fan, you can use that to blow gently on the plants. This simulates wind and will stimulate growth in the stems that help with standing upright. I have a small one in my grow tent that is on a timer so that it turns on and off at various times and it sweeps back and forth. Because the area in the tent is small, I angle the fan up so it doesn't blow directly on the plants but will get them moving like a breeze would do.

Thank you

Sean