Electrolysis is a funny animal. I've seen propeller blades where one is  half 
gone and the other is just fine. Very little reason for why it does what it  
does. You just need to be careful about disconnecting any battery power when 
you  leave the boat or it will find a way out. Raising the motor completely out 
of  the water is an easy way to prevent electrolysis through the shaft. Shore 
power  presents a whole different set of problems and I won't go there.
Coating the bolts to prevent seizure sounds like good preventative  
maintenance to me, especially with a new expensive four stroke. You have  dissimilar 
metals in that area. The bolts are stainless and the housing is  aluminum. The 
problem is even worse if you are in salt water.
 
Rummy