I want to start by saying that I don't know much about cars so apologies if this is a silly question. I will try to give as much information as possible in case it helps answer the question but most of it will probably be unnecessary.
I have a Lexus is250, 2007 UK Model. I have had the car since last August and never had a single issue with it, it's been perfect. I drive about 100miles a week, normal street driving in London, no motorway driving. Yesterday I was driving around in my car and as always no problems. Last night whilst driving home I was stuck at traffic lights on a hill and I think I stalled as I pulled away, the engine cut out and after several attempts trying to start the car it wouldn't start back up. I had the clutch all the way down till the green light came on the start/stop button however everytime I tried to start the car the check engine light came on and the battery light but the engine would not start up. After about 10 - 15minutes the car started up properly, no warnings lights stayed on and the car drove home without a single glitch. I popped the car around to my mate at the end of the road who is a mechanic and an auto-electrician, he had a quick look under the bonnet (it was like 11PM and he was really busy), and he couldn't see an issue. I turned the car off and it started first time every time, tried this about 7 or 8 times and everytime it started without an issue and no warning lights. My mate said it could be that the car was doing a self check after it cut out and that is why it wouldn't start up straight away.
At the time of the car not starting the engine temperature was about half and there was 3 quarters of a tank of petrol (I very very rarely let it go below half a tank), I last topped up petrol Monday. Coincidentally the car had hit 66,666 miles when this happened. The car has full Lexus service history and is due to be serviced and MOT by Lexus is July.
My partner took my car for a quick drive this morning and she said she didn't have any issues and no warning lights, the car drove perfectly (neither of us know much about cars but did not feel any obvious operating issues).
Is this something I should be worried about? Thanks in advance for any advice/help.
Apologies for such a long post just wanted to provide as much information as possible.