Did I make the roll too easy?

[JMISBEST]

Something that occured in a 1st editon Pirates of Drinax Campaign a few years back and could occur in 2nd edition is that The Pc get The Pirate Starbase at Wildeman then do Deamons Eye and bargain with Tech-World to have their Starbase make 5 400 ton and 2 500 ton Ships with Tech-World paying half upfront and The Pcs persuading Oleb to loan them the other half to be paid off when possible. I liked the idea so much that I let them try, as they role-played it very well I decided they needeed 12+ on Persuade +Social Scale of 2D6+4(Persuade /2 and Social Scale 12), they got a 11 and in order to change it to a marginal success they agreed to the condition of leaving 400 tons of ships behind as insurance. But as I hadn't got much experance at judging how easy or hard the roll should have been back then did I make the roll too east