R.I.P. chipmunk

We've been working hard on our yard since we moved in in October. We're not there yet on by any means, but we have bird feeders with carefully chosen seed and water accessible to the birds and wildlife. We don't spray herbicides or pesticides, because they can both be ingested by birds and wildlife.
We have tons of birds that fly around our yard, despite the hawk that considers a pine tree his buffet. And there are three bunnies that like to chase one another around maniacally.
But our favorite furry guys are the chipmunks. If you create a cubic foot of dirt in a new place on the lawn, there are chipmunk holes in it within an hour.
The little guys love to run around the yard, perching on high points. They tend to congregate near the back door, running for cover when we leave for work.
But today, my husband came home to find one of them dead.
He was lying in the driveway (the chipmunk, not my husband), and my first fear was that I had run him over. But he looked OK, aside from not being alive anymore, my husband said.
I feel terrible that my husband had to bury the sweet little thing. But I'm so relieved I didn't see it. I probably would have cried and gone door-to-door demanding to know if someone was spraying something in their yard.
Do we know it was chemicals? No, but it does make me think twice. The makers of Roundup say, "For liquid products, it is generally safe for wildlife to return once the products have dried." But who tells the chipmunks to stay off of it until it's dried? And why is it "generally" safe when dried, not just safe?
Chemical sprays seem like a quick and easy solution. But the next time you reach for Roundup to deal with a weed, think about the chipmunk that doesn't know that he should be in my chemical-free yard instead of running through your sprayed weeds.