All 3800s and 3200s are PRE 2014 -- no exception. The wording of the law is complicated to say the least (which law in recent times isn't?). They cannot call something a 2014 model unless it's a T4, as such it would be L3301 or L3901 as Kubota's T4 are called. Without knowing Kubota's actual production cycling, and assuming it goes with the actual calendar year, they couldn't make (install the crank in) the T3 engines after the last minute of 30-Jan-2014; and that's only if they called them 2013 models.
Now as to the actual production date of the unit you buy, which really doesn't matter nor is it easily found out, it's safe to assume that it was built between 2012 and Jan of 2014. I doubt you will find any differences in any of the 3200 and 3800 models produced between 2012 and 2014 as Kubota knew the absolute end of production date for the machines and most likely would not spend money retooling for such a short production run.