Sounds a bit high for a 508 mile flight, assuming he went nonstop from SLC-PHX, which only nets him over 1,000 lifetime flight miles RT.

i just cashed in 44K miles RT from DEN-TPE and that earned me over 14,000 lifetime flight miles. I earned 13,000 more lifetime miles for just 5k more SkyMiles and international taxes.

A word of advice early in your Delta flying career: always aim for longer distance DL metal flights when using SkyMiles so you can get more miles towards lifetime MM status!