Presumably the OP is viewing the seat map and when he/she sees a seat become unavailable the assumption is that someone got upgraded. But there's no way to tell and more than likely someone with a purchased J fare went in and chose their seat. As noted seat maps on aa.com can be unreliable. Consequently, the number of seats available for upgrades would be limited.
I would imagine on that route there's no shortage of higher end leisure travelers willing to shell out big bucks to get out of the hell that coach has become, particularly on a flight to/from OGG. In more so if there's lie flat seats, which AA will advertises on it's website.
Alternatively, these may have been upgrades that cleared by SWUs or copays. There's just no way to know. I would say any route to HI depending upon a complimentary upgrade even as an EXP is risky. Shell out the money for J or PE if a widebody.