TIMTS,
If you follow this link, select "Safety Information" on the left hand menu then scroll down to ACAS Bulletins. There are 6 of them and all well worth a read. They explain operational situations
http://www.eurocontrol.int/acas/[/URL]
The information displayed to the pilots on a TCAS display often lags the real time situation and if the crews were using their display literally this would give them the, false, impresion that you were a treat when you had infact cleared the area.
It sounds like you are operating professionally and sensibly.
Regards
MM