According to the official Obligation chart
on the website, a roll of 72 is 'Favor'. You owe someone who helped you out in a big way at some point in the past, and they fully intend to call in that favor in the future.
Of course, it's only off by 1 from Oath, which I'm guessing is what you were going for... Right? ^^; It certainly would be fitting for your character concept. During the time of the Empire, the Antarian Rangers largely concerned themselves with locating and hiding away force sensitives from Vader and the Inquisition, particularly surviving Jedi, so that would certainly leave you with a nice, ready-made obligation to start with...
The next question to think about, though, is what would such a character have done that would leave him working for Vinny the Hutt?