Classtime thanks for these tips and the link to Tire Alert.
This was actually my first time to ever use a sealant on a new, unridden tire (I've used Vittoria Pitstop a couple of times while out on a ride, with mixed results).
The tire held air when I pre-stretched it prior to gluing and adding the sealant. I'm assuming the leak is at the valve stem because that is the only part of tube which has seen any stress when I inflated the tire.
I did email Excel Sports (where I purchased the tires) and have had no response so far. I plan to email Vittoria directly if Excel Sports doesn't offer me anything.
Since I only paid $39 (tire+shipping+tax) for a tire which has a retail price of $130 (before shipping and tax), I will still be ahead if I send it to Tire Alert and have them replace the tube for another $39 (their price + my shipping). Or I might just try replacing or patching the tube myself.