When you make your batches, how much do you use at one time? Hope I didn't duff on it. My apologies if I didn't you justice. We'll see. I may even place in the fridge for a few minutes as well.
I usually use a tablespoon of mix at a time, but I have done smaller amounts with no problem. As I've said, I usually put the mix into a drinking glass, add the (warm) water, let it sit a minute, then nuke it all together. Sometimes I've been impatient and poked it early and gotten some on my fingers, but I've never had a problem with it setting once it was fully cooled.
How bout another question....
If it's not quite right, can it be re-heated? Maybe add a skosh of water?
Absolutely. You can melt and re-set agar to your heart's content. Eventually, you'll break down all useful nutrients in the veggies, but I would think you could go 2 or 3 rounds at least without too much loss.