What did Roger mean here?
Depends on a bunch of different circumstances, I personally think the simplest guess is that Roger simply lost a fight against him during the year and it bruised his ego. GV happened 38 years ago. Roger pirates found Lodestar 39 years ago, learned they needed more info to find Laugh Tale. Some skirmish happened between/during this time frame.
There's the impetus for the GV incident itself -- the "crown jewel" stolen from Hachinosu by the WG to presumably be used as one of the six chest rewards on God Valley. Whether it was a fruit or an item is unknown, we know at least two of them had the Azure Dragon fruit and the Paw Paw fruit, the contents of the other 4 were never revealed (I discount that one of them had baby Shanks in it despite what was shared in the special Film Red volume because I think that'd be a dumb as hell prize lmao).
It could be that Hachinosu's "crown jewel" was a potential key or clue for the journey to Laugh Tale, and that Roger and Rocks fought over it at some point during that 1 year of discovering Lodestar and fighting on GV (and Roger lost or couldn't win). Though I think that's a shoddy guess and I could be totally wrong because I am a dumbass.
P.S as a non-sequitur: it just occurred to me Blackbeard is 40 years old, and GV happened 38 years ago, meaning Blackbeard was born while Rocks Pirates were still an active group and WB was one of its members. The mystery of the bastard Teach deepens, Rocks musta been a piper.