I guess it depends on how tough a life your GS has lead so far. If she has had plenty of off-roading, urban kerb-hopping etc then she may need a little fettling to restore her crisp steering.
It could be a simple as worn front wheel bearings. I guess you will have to put her on the centrestand and start checking everything for excessive movement at suspension and steering components.
I did a full chassis strip and rebuild of my Yamaha due to weird handling ( caused by negelect by the previous owner ) including swingarm and headrace, shock and linkages, fork strip revalve and rebuild with uprated components, wheel bearing replacement and the difference was nothing short of remarkable, handling and stopping is now better than new.