Wouldn't be surprised. Having done this myself, it takes about 10 minutes for the oil to drain to a drip. I'm surprised they wouldn't charge you for a full 10 qts though. Was this at an actual Lexus dealer?I have a feeling they didn't allow the oil to fully drip out and just changed out 7 out of 10 qts.
I called the service dept and they told me that an internal charging code only allows for 7 quarts to be entered into the computer. They said in actuality 10 quarts was exchanged. Does this sound credible?