If I leave a non-polar solvent to evaporate to reduce the amount will any of the DMT inside convert into oxides?

unless you use fan and heat, I would say only an insignificant amount of dmt will oxidate (and even doing that, it also doesnt necessarily oxidize).

I dont have an analytical equipment so I dont have numbers to quote, but I do know that when I used to extract with naphtha and pre-evaporated the naphtha before freezing, the yields were still high as expected, with white crystals, so this pointed to the fact that no significant amount of n-oxide was forming.

Thanks for the info. I was guessing even if it does it is not that much, but I was just curious if the fact that it was in a solvent would protect it from that.