unexpected LUID error

hi folks -
anyone got an idea what this line means in the event log?

12:50:26 UT : 09/03/02 : File C:/ISIPPC/pssppc.250/bsps/devices/whisp/session.c : Line 4300 Drop session, unexpected luid. ESN = 00-00-00-00-00-00

several times over…
this is in a cluster of 5 ap’s… every AP gets these messages sooner or later.