Redsand-
No, if it's realtively clear, then the seals (o-rings) are still good. Although the shock oil may thin out somewhat, I seriously doubt that anyone could measure enough difference to where it affected performance.
The oil in your shocks are not subjected to the extreme temperature changes as say motor oil (which is used to lubricate and cool the motor). So, with the minimal amount of movement combined with the lack of heat generated from the internal moving parts of a shock means that the oil should last a long, long time without any denegration.
Seepage (loss of volume) and contamination are more of a "real" concern as those factors greatly affect the performance of a shock.
If thinning oil in the shocks were a concern, we'd all be taking our cars (real ones) in for a motor oil change and shock oil change. The fact that we do the former, but not the latter tells me that shock oil thinning is not a concern.
DT