Brake Light and Battery Light come up when the car is cold on 2003 Nissan Altima

For the last 2 days I am noticing that the Brake Light and the Battery Light come up and stay for around 2 minutes when I use the car first thing in the morning. After that it goes away and the car runs fine. I got the battery and the alternator checked and the mechanic told me both look fine. I notice that it happens when the car is cold i.e. idle for a long time. If I am driven for some time and then If I start the car, it does not come up.

Any help to look in the right direction will be appreciated

Asked by for the 2003 Nissan Altima
1 answer 1 comment
replace the alternator.

Has the alternator gone bad or in the process. Can I wait for sometime or will it need to be immediate