Apparently the old gal must have had a momentary lapse of reason and the code was dissappeared on its own.....for now.

Update: I am very suspicious that this code was caused by low tire pressure. All of my tires were low by at least 5 lbs. My TP light is disabled so if the tires are low enough the wheel sensors may not read properly and after refilling, taking time for the code to self clear. This is just my hypothesis at this time. For the record here were my symptoms:
2 P0500 codes - stored and pending. After tire inflation the stored code was eliminated but the pending one remained. Residual P0500 cleared after a driving a few miles after tire inflation..
- other indocators: Check engine, ABS, BAS/ESP
- cruise control non functional
- spoiler wing deploys on startup and wil not retract manualy until in park.