You guys had bad timing. While it hasn't been a great spring there are some snakes moving.
There have been two recent rain events in portions of south Texas. Keep an eye on the weather maps so you know where it rained, when it rained, and how much it rained.
This past weekend the dry line pushed way east of San Antonio and we had high pressure and cool nights. That's not a typical 30 snake night in south Texas. I didn't look to see exactly what it was doing when you were there but I do know portions of Duval got between 1-2" of rain.
I believe it has recovered already and should be back to semi-normal this week, if you stick to areas that got at least a little rain and don't look like they are a matchstick away from being torched.