Date of manufacture and sell date may be different years.
That may be the problem with the date.
a simple mistake, no big deal.
Now, make sure you get any service records he has.
You'll probably ride 100,000 trouble free miles.
BUT...
You may not, anything can happen, not the owners fault, your fault or alot of time not even triumphs fault.
IF something does go wrong after you get it, you're in the right place for a knowledgable answer to any problem.
AND Triumph has been stepping up to the plate and paying for any known problems.
That's a big plus in my book.
Now for price.
Have two in mind.
The one you'd like to get it for,
and full price he's asking.
After your test ride y'all may not be that far apart..

oh yea,
WELCOME to the forum..