I always remove or at least tear the netting. The netting on the brands available around here, Jiffy and Ferry Morse, doesn't decompose well at all. I find the plants do better if I at least partially remove it.
May Day is when we start losing the lettuce to the heat. Every week the heat stays low enough not to make it bitter is a gift. I only plant leaf lettuces so I can eat along all spring. Mine should have been out in the cold frame a couple of weeks ago, but this goofy weather made me nervous about...
I get them sometimes when I eat something hotter than my comfort level. One of my local heat eaters doesn't consider it good unless it gives you the hiccups.
Pepperfreak had the same problem, if I remember correctly, and had it diagnosed by Ohio extension folks. Paul? Does this look like your plants did, or do you still have pictures?
The droopy bottom leaves and spindly stems are the same problem...not enough light. Do they ever produce fruit? What's the NPK ratio of your fertilizer? If the N number is higher than the others, it will encourage lanky growth.
And if the pots don't drain, you're setting up the perfect...