At the moment I am having real trouble getting my Diamond Touch to get a lock on the GPS position, so I often start the run without the GPS locked in. About 5 minutes later Run.GPS kindly informs me that the GPS signal is good and then will start to announce my pace. The problem is that it takes the average pace as "total GPS distance / total time" so in the first announcement I might have spent 10 minutes and gone a mile, but Run.GPS will announce that the average pace is 4 hours something as the GPS only thinks I have gone 100 yards.
As the average pace only takes into account the distance from the GPS, it should really only take into account the time since the GPS lock was acquired.