Trying to decide if it is necessary to trap the hickory on a 2 piece HBO take down. I have glued the hickory to the osage, cut it in half, glued the brass sleeves on and am ready to lay out the center line.  Thoughts?

I would say, not necessary, but depending on the size and shape of the bow, I might do it anyway, or do it slightly.

Nah. You cant hurt either wood and they match up absolutely perfectly just like you have them. Hickory wont break in tension and good luck getting any frets with osage if the tiller is even half close.

What Pearl said.  

I also usually sand any sharp edge of the backing so as not to catch a splinter later.