Only here a click when starting engine.

[forestb]

So my 62 C10 has been running and starting great. I was driving it on Saturday and parked and turned it off and couple of minutes later I tried to start it again and all I heard was a click. It didn't even try to turn over. I had over 12 volts on my voltmeter. I tried to use a jump pack to start it and it didn't help. Radio still worked. It is a 350 with a 700R4. Battery is fairly new and the alternator was rebuilt about a year ago. My initial thought is that I need a new starter motor. I am going to check all my wiring first but I was wondering if there were any other thoughts before I start replacing parts. I was also wondering if it is possible for the gear on the starter to not engage with the gear on the fly wheel or run into them when popping out. I found it strange that it didn't start and then 15 minutes it did start. Nothing was moved or wiggled. My only thought is that it cooled down and then it started.