Thanks to various authors telling different versions of that encounter, I'm pretty sure the EU version of events had Han running into every bounty hunter in the galaxy on Ord Mantell at one time or another.
As I've already stated though, the decision to carry forward the Jabba plotline from ANH happened during the development of ESB's script. It's purpose wasn't to resolve Han's epic and highly relevant "financial dealing arc" (coz there ain't one!) it was to give Han a compelling reason to have to leave the rebellion and thus drive up the romantic tension between him and Leia. In the earlier drafts it was the Alliance asking him to go see his estranged step-father and ask for his support (he was some bigwig that controlled most of the major shipping lanes or something.)
That was a little dry and convoluted, so they parred it down to "he has to go get the price on his head removed".
It was not something Lucas deliberately left dangling to be resolved later when he wrote ANH. Indeed, Had Ford gotten his way and Han had been killed off in that, movie, they we would never have seen Jabba at all and he'd remain just a passing mention and not at all involved in RotJ.
This is what happens when stories build on each other. Inconsequential details in earlier instalments start taking on more weight and consequence in later instalments. In the initial conception of ANH, the Emperor wasn't the ultimate face of evil, he was just some figurehead/puppet ruler controlled by "greedy trader barons" and the real villain of the piece was a moustache twirling, corrupt majordomo type character that would later evolve into Tarkin. But then they killed him off so they needed a new boss for Vader, and the rest is history.
