I'm 99% sure it's not overwatering. This plant was bone-dry and needed water. I watered a bit faster than usual and put about 3/4 gal through the 5 gal pot... just enough to start to get runoff.

I've got my watering technique down. I use the "lift-the-pot" method to determine when to water. And I confirm with a moisture meter (at least until I get the feeling for the specific soil/pot I'm using). This plant is one of the largest and I even let it sit pretty dry for a day or so before watering (however never long enough to show signs of underwatering).

Anyway, do you guys think colder water could cause this (temporary) drooping? I'm guessing the water was between 55-65 degrees. I'm sure the plants will look better in the morning. But I should probably invest in an aquarium heater and thermometer to make myself feel better.