Found it I think!
"Based on the number 1177F28-29 I am able to determine that this battery was formed on the 177th day of 2011. The first digit in this sequence is the last digit of the year and the next three digits are the day of the year.
Regards,
Spencer DeTurk
East Penn manufacturing co., inc.
Lyon Station , PA 19536
(610)682-4231x2993 "
So my 9308s are 2019, 308th day. I also read somewhere that with Wets, they make the forms and date them, but add the acid later just before shipping them and put a shipping date sticker on then. One guy said they might start using next month's stickers "early" around the 20th of a month.
So my OP batts check out for their dates ok.
Got SG up to 1.295ish in the cold, so Baseline will be a tad less than that. I am calling it 1.290 for government work.