Since it was a trade in, I have no way of knowing. It has been to Lexus every 5k since new but no mention of tranny service. It does have tow package but looked like all of the jumper harnesses were still in the packaging in the glove box.I didn't to my first "flush" till over 80k. At 123K, I just had it flushed again with a full service, including having the pan removed.
Unless there's been a lot of heavy towing with it, personally, I wouldn't worry about it.