Here is the TSB on this issue. However as you state this only happens after you fuel up would make me want to check the EVAP purge solenoid on the engine for proper operation.
Starter Cranks After Key Is Released (Normal Condition)
2003-2008 Passenger Cars and Trucks (Including Saturn)
2003-2008 HUMMER H2, H3
2005-2008 Saab 9-7X
Attention: This bulletin ONLY applies to vehicles with PCM/ECM controlled starters.
Some customers may comment that the engine starter will continue to run after the key is released.
For the 2003 through 2008 model years, the Powertrain Control Module (PCM) or Engine Control Module (ECM) controls the starter relay based on input from the key switch. When the ignition switch is held in the start position for 0.4 seconds, the PCM/ECM start timer is activated. Once the start timer is activated, the PCM/ECM will continue to crank the starter until either the engine starts or a no start time limit is reached.
Occasionally, the fuel pump module will take one or two seconds to build fuel pressure. Often this will occur after the vehicle sits overnight. During some vehicle starts, the customer may release the ignition switch key before the engine actually starts. When this occurs, the engine will then continue to crank until the engine starts or the no start time limit is reached.
This is a normal condition and no repairs should be attempted for this condition.
Friday, March 17th, 2017 AT 11:09 PM