I have a 07 ES with about 46k miles. I noticed a small amount of oil on the garage floor. I monitored the leak over several weeks. It would amount to about a teaspoon or two over several days. Looked under the car, was not the oil filter or oil pan drain bolt. Leak appeared to be just behind the oil pan.
Took it to the Lexus dealer. They called the next day and said they needed a extra day or two. That made me a little nervous. They actually kept it for about four business days.
The leak was at the backside of the gasket for the timing chain cover. Apparently, during assembly, the guy that was supposed to seal the timing chain cover was not having a good day. When I got the car home, I started to read the service ticket. The parts required included: oil pan plug, sealant, oil filter, 7 qts oil, gasket, coolant, O-ring, another gasket, brake fluid and transmission fluid. Upon inquiry, I learned that they had to remove the engine and transmission out of the car to make the repair. They dropped it down to remove the engine. Fortunately, my Lexus dealer service department has an excellent reputation. The TSB covering the repair is EG010-07. Had the engine been out of warranty, the repair would have cost about $2200.
I'm sure glad I didn't ignor a very small oil leak.
I also had the oil hose failure a couple of years ago. They fixed that as well.