Congratulations on solving the problem! It's a shame that your amp is defective, but it is very fortunate that you decided to roll 408A tubes now, and not a year from now, so you are able to make a strong case for a refund.
7.2v is a little high, but that is not surprising. The LD heater voltage is unregulated, so if the AC voltage coming out of the wall is a bit high (not at all uncommon) the heater voltage will also be high. Plus, with no tube plugged in, there is no load on the heater circuit. Typically, with a tube plugged in, the reading at the pins will be a bit lower. Anyway, nothing to worry about.
And IMHO, your decision to purchase your next amp directly from LD is a good one. They have one of the best warranties in the business.