I'm going to say no, so long as you reconst with bac water. It will take a lot longer than overnight and other environment variables like direct sunlight or considerable raised temp to ruin it.
If you ever have any doubt and want to confirm if still good just do a mega dose of ghrp6 and if dont get gastric sides then you know its toast.
In all truth, I actually doint refrig mine, except for during like the summer months depending on where I store and how hot it gets. I just keep in a dark and for most part cool area and they stay good to go. I go through it too quick for it going bad.. I think the longest I've let a reconst vial sit for between use is prob a few months, ghrp6 too, and still is same as before. I did a 200mcg test dose and bam gastric effect in no time LOL