Unless you got an impression from the seller to be suspicious, the title was probably done in error, but good faith.
1972 was the year boats started having a HIN, Hull Id Number, similar to a cars VIN. It was probably sold after 1972, or all boats were required to get a HIN by the state at some point and their method of assigning a year for older boats was to choose to title them as 1972s.
Happens all the time. I bought a 1960 boat that was registered as a mid 60s, but from a no title state. It clearly wasnt a mid 60s. That boats styling was only used for 2 or 3 years and it was drastically different after 1962.
Only matters if it matters to you. It isnt easy to change a title in some states. In others its not too bad.
I had to jump thru hoops here in WV to title it, regardless of the registration,, so when I jumped, I jumped thru enough to just get new title and registration for it as a 1960 boat.
Where are you located? Buy it from out of state? If so, what state?