Long, 32, left the Warriors in 1997 before moving to Knowsley Road via Widnes.
He recently signed a two-year-deal with Hull, but claims he could have returned to the JJB Stadium.
Long said: “I could have played 50 yards up the road here and lived in the same house, but I wanted to make it a new challenge for me on all fronts.
“And if I’d gone to Wigan, it would have undone all the good I’d done at Saints.”
Long left the Warriors in 1997 in a deal that saw promising Widnes forward Lee Hansen move to Wigan.
The Warriors are in the market for a half-back owing to the expected departure of Tim Smith at the end of the season, and they have been linked with Melbourne’s former Parramatta scrum half Brett Finch.