My son is a masher too. But he's young yet and can get away with murder.
he is amazing going up a hill on a fixed gear bike.

I think you can train yourself to spin more, but to an extent, you're always going to tend towards mashing if you are one... so with this knowledge, you
can improve and i'm sure it will be just great.
Congrats on the new bike. I hope i get one soon. as soon as i figure out what it is that I want.