DS4 doesn't try to write mirror writing. You're right, trying to do it on purpose is a sign of an active mind and a creative kid rather than anything that's worrisome.
That's not what's up with DS4, though. I'm sure of that. He doesn't realize he's writing in total mirror reversal. That is a bit worrisome...And the fact that it's not an isolated letter reversal here or there, but is whole words, numbers, etc.
Still too early to tell, though. I'm just biding my time and keeping my eyes and ears open.
Thanks for the info, 'Neato. I like having more ways to put all this into perspective.