weird starter issues

[Garthc20]

So I wanted to change my oil today and went to fire up the truck and nada, I checked the battery and it read 12.5 volts so thats ok and it is only a month old , checked the cables and it all seemed ok . then tried to jump it with the jeep and still no luck . next I tried the old screwdriver trick and nothing, so Im thinking the starter is fried , take it out bring it to auto zone get it tested and they say Its fine WTF. bring it back ,re install , man they do get heavy after a while. clean the positive cable and crimp the cable end , do the same with the ground and cleaned the battery terminals . tried it out and nothing again. so I hooked it up to my charger on 6amp and let it sit for a couple of minutes and then she fires right up . I turned her off and started her a few more times just to see if it would repeat but it seems to work now . the only thing I can think of is I cleaned the case on the starter with break cleaner and maybe it was still wet? needless to say I still have to change my oil I guess theres alway tomorrow