Hi Matthew,
Did this ever happen again for you? Did you find a resolution? My car just did the very same thing when I went to leave this morning. Hadn't been run for 4 days (had the flu over New Years', sux), with overnight temps around 30F (-1C) every night.
I only left mine running for a couple of seconds at a time for three start attempts, as it sounded so bad I didn't want to leave it running. Obviously you had a bit more pressure to leave it running (gotta get home from work somehow!). My oil is due for a change (I use full synthetic Mobile1 and change it every 8K or 10 months, whichever comes first), but it still looks fine (nice caramel color), though it does look to be a little low (it's right in the middle in between the two dots on the dipstick).
My car is a 2005 IS300 US-model with 66,000 miles on it. No repair issues with it to date (it's been a dream, love it).
I'm thinking I'll wait until the afternoon when it will be warmer and try it again. I'll post the results after doing so.
Thanks gang,
Terry