I bought this car about a year ago, it only had 22K miles on it. Everything is great except one problem. Every now and then when I put the key in, it won’t turn over. I have to take it out, wait a few seconds, put it back in and it starts right up! I tried to search online for people having similar problem and found one person that complained of it happening in cold weather. It does seem to be more frequent now that the weather is colder (live in michigan) but I don’t know if that is due to weather or problem getting worse. I don’t know if this matters but it does have the security device where the car won’t start without the key.
I have a warranty but I would just like some more information before I take into shop.
Thanks for any help/advice!

(Brake Light Switch) I would check to see if the brake lights are turning on. If you can move the shifter into neutral the brake lamp switch is ok and signaling the shifter release. Other than that if you take it to the dealership it will always start right up. (cars do that) Good Luck
Nissan has major problems mainly with the Altimas but also Sentra with the brake light switch failing.
I would check that first, second thing that is common is the crank sensor..
It your engine wont turn over when you turn the key it sounds like it could be a security issue. Does you security light come on after the car starts?