No, you're not overreacting! Thank dawg you caught it quickly. I don't know how toxic per se the stuff is, but it's very caustic and can cause burns. Did you check her paws well to make sure they're not burned or irritated? You might also want to check her mouth and rinse it with water for good measure if you noticed an irritation. If you see anything, a quick call to the vet is in order.
Hope she didn't ingest any, MWW! And welcome back, stranger.