This is most likely the case starting with the 2005 style and up Odysseys.

I bought my 2006 Odyssey used, was prompted some random day for a pin to my NAV, I never set a pin, but there is a pre-configured manufacturer pin number located on a non-labeled sticker in the glove box. I had 2 stickers with 2 random codes on each, 1 being the 4 digit pin to the NAV!

Hope people find this useful.