Nah, I think there must have been something.
CHEWBACCA: Grunts.
HAN: Well that was a long time ago. I'm sure he's completely forgotten about that.
...and...
HAN: (To Leia) See? My friend. (To Chewbacca) Keep your eyes open, huh?
And of course, the fact that Han won his ship. I like to think there were other hiccups in their friendship, not just the ship. Perhaps Han "borrowed" a cup of sugar and never repaid.