I think that at room temp for 16-24h it shouldn't be a huge concern. There may have been limited denaturation, but you'll still have enough intact GH there for at least a partial effect.
If you had left it in your car, in the sun, with the windows rolled up, on a black leather seat... well, I'd say open it up and water one of your house plants with it. HAHAHA!
Should be fine, bro.
-M