2009 Mitsubishi Lancer - Random No Start

My car would not start ?
Got my day started yesterday as I always do. Car turned on fine in the AM. Went ran some errands… still no car issue.
before heading to work I stopped by the bank, when I got in my car to start it, it would not start? Radio, lights all turned on. I called AAA… the guy gave power to my battery… still would not start? He then said to lock and unlock my car then turn the key to start car ? nothing ? He took my key fob turned the key several time.,… Bam turned on ?? strange… He said it sounded like my starter is in the 1st stages? not sure.
I took the car home… When i got home from work i went to see if it would start? It did with no issue? ok, good.
In the morning today 08/08/2019… I again went to turn on the car, bam turned on with no issue ??
What could have caused this ? How can I fix this ?