I haven't let the vehicle go more than a few days without it being driven so I've been fortunate that the battery draining issue only occurred once in the three months since my purchase. Since I live in cold climate area of the US where temperatures in Dec-Feb drop well below zero it's quite possible that's a contributing factor to the battery drain issue. That being said, I'm apprehensive about letting it sit around for more than a few days and I'm not confident it won't happen again.
Regarding what Taffy13 mentioned in their "Post Script". I did take go to the the dealer and the indeed they indeed asked me if I left any interior lights or if the doors or back hatch were ajar (for the record, everything was locked up and nothing was left on). Furthermore, they also stated that this *never* happened before―then proceeded to tell me that *most* Lexus owners drive their cars everyday. I was a bit insulted that they weren't more honest, but they're a car dealership (i.e., the epitome of dishonesty with the exception of politicians) after all, so it wasn't a big surprise that Taffy13's predication was my reality.
If I do run into this issue again, I'll be sure to post again.