I think This is the Third thread on this in as many days, you don't have to get service right away, just have the SID reset...
Yes this does happen on occaison, just have your dealer reset it and go in for your first Intermediate Service at 10K on the odometer. They'll reset it again then and all will be Hunky Dory.
Main Services are based on actual mileage, Intermediate services use the Algorithm.
Excerpt from Saab TSB:
INTERMEDIATE SERVICE is set by an algorithm that determines when service is required. Miles driven, crankshaft revolutions, number of starts/cold starts, ambient temperatures, speed and engine temperature are among the measurements used to compute the interval with the TIME FOR SERVICE message being set between 8,000 and a maximum of 15,000 miles.
If the mileage interval is not met, the message will be set at 2 years.
NOTE: The actual oil condition is NOT measured, only the above calculations performed.
SOURCE;
http://www.genuinesaab.com/psi/
There has been a past issue with the TFS message in the SID, see the link.