Spatial query with 'dynamic' dataset

[Lalonde Marc]

Hello all,
I'm trying to execute spatial queries with jena in the following 
context: an object's position (lat/long) is updated on a regular basis 
and I run a query ("SELECT ... spatial:withinCircle()...") to verify 
whether the object is close to a particular point of interest. I 
simulate the object's motion by increasing its long coordinate; the 
associated model is removed (i.e. spatialDataset.removeNamedModel() ) 
and recreated with the new position; content of the Lucene indexing 
folder keeps increasing. What happens is that when the object gets 
within the desired radius, the query returns a result (which is good) 
but I keep getting a result even though the object has (eventually) 
moved beyond the point of interest + radius. Could it be because model 
removal causes the spatial indexing to be out of sync? I use 
"RDFDataMgr.read(m, file)" to load an updated model to the dataset.

Thanks,
Marc