If you’re looking at your reservation, chances are it’s an error. It’ll likely go back to dinner at some point, and might change several times, including items like snack, or even Meal: 2 or meal: 5.
Best way way to check is by doing a dummy booking to see what it says, or looking up flight status for today’s flight ariund the same time. I just realized you said the flight was 4:30, which today is listed as ‘light snack and beverages” (E75). The 5, 6 and 7 flights, all main line, show as dinner. However, UA and UAX should be consistent based on time of departure - with UAX getting a cold dinner (no ovens) either a cold sandwich or I forget the typical other option, and mainline getting hot food. I’m not sure the breakdown of times for those exception flights (since its technically under the mileage limit for meals, but is an exception route), and if the 4:30 ever received dinner.