2005 HCH, just a tad under 40K miles.
I've never had any problems with the AT.
Today as I was cleaning around the battery tray, I looked closely at the tranny housing. What I saw was not good. Over the surface was fine webbing, like very tiny cracks. Check out the picture and tell me what you think. Look at the center, top, and upper right. The pic is focused above the tranny fluid cooling line. Should I be concerned with this? I don't see any webbing like this on the engine block.

 

I've seen that before. It's likely just casting surface irregularities emphasized by grime. I'll check my 2X HCH2 this evening.

 

I asked my brother who's worked on some before; he said it's normal. Also checked some other Hondas...it seems like a pretty common occurrence. It's even on my folks' '02 Accord engine block, and they never had trouble with it.
I'm the 2nd owner, and the underside is scratch-free.
For a while there, this was causing me some concern.