My 6i didn't have a date code either.  I did the SB as called out by Horizon and found that the pots seemed to be fine.  I called Horizon anyway and was told that I should be good to go but if I would like, send it in and they would check it out. 

If you're unsure, I would send it in to be checked.  No sense in wondering only to suffer an untimely/unfortunate crash and experiencing the "if only" syndrome.

Just my thought.