Got a P030X on the third day with my '07 GXP when new.
Car ran like a champ, code went away by itself the very next day as I recall although I do remember exactly that it happened on the thursday aftyer memorial day 2008, just past the Dunkin Donuts near Forest Hills T station. It's strange what you can recall. Brought it to the dealer anyway, they could find nothing wrong but they ID'd the code, which I cannot accurately remember other than P030something. Only explanation anyone could come up with was some bad gas. I miss Rickey Smith Pontiac, they were a pretty good dealership.
Driving and working on a Sly 2008 Solstice GXP 5spd 260/260, and the worst-built 2012 LS3 Camaro 1SS to escape from Oshawa.
Gone but not forgotten:
2007 Solstice GXP 5 speed 290/340
Stored and needing to part ways with a 1970 Skylark Custom convertible I have owned since 1989 and turned into a GS455 clone. 462 with 7/8 primary headers, adjustable roller rockers, TA Performance Stage 1 aluminum heads, auto, Chevy 12 bolt, 3.31:1. Sadly a project car now but a driver from '89 to '06.