I WONDER WHY I JUST THOUGHT ABOUT YOU?
If a random person pops into your mind you need to pray for them—at that instance. What may seem random could be very specifically planted by God. It could be urgent. And even if it is random, they still get prayed for.
When you can't get someone off of your mind first pray, then call and say, "I can't get you off my mind. I’ve prayed for you and wanted to call and see what may be going on in your life." You will be amazed at what you hear.
God sends all kinds of clues and messages to those who are inclined to hear them.