Well if you have been watering in the evenings, and the plant got wet, you could have picked up a leaf fungus.
Never water at night! Morning only!! Never wet leaves.

Fungi have incubation periods, during which a source of moisture is important to their continued development. It's fine to water in the evening, but you should try to be sure the foliage is dry before the dew point is reached as dark approaches.

Your problem is probably related to too much water. Try watering only in the AM or PM, not both. You might even be able to go much longer than a single day between waterings. Maybe, after watering, you could watch your plants closely for signs of wilt before you water. I'm not suggesting that as a regular way to tell, but knowing how long your plant CAN go between waterings is useful in figuring out how long they SHOULD go. Especially with peppers, it's better to err a little on the dry side rather on the side of a soil that's continually too wet.

You can also sharpen a length of 1/4 or 5/16" wood dowel in a pencil sharpener and use that to test for moisture deep in the pot. If it comes out dark or wet - no need to water. Also, FEEL the soil at the drain hole with your finger. If it's wet - no need to water.

Al