See http://www.aprs-is.net/q.aspx

Packets with q-constructs have passed through the APRS-IS.

However, if you're only viewing stations received on RF, don't panic.  This view option shows stations that were received at least once recently via RF.  However, the popup information is derived from the most recent packet received which may have been via the APRS-IS.

And also do not worry about receiving packets from the APRS-IS even though you might not have a filter, or the packet doesn't seem to match your filter.  The APRS-IS "filtered" port (typically 14580) is actually an "IGate" port.  It will assume that the connection is from an IGate and any station whose packet that you've gated into the APRS-IS will be added to the server's "recently heard" list.  For some period of time (30 minutes to 2 hours or so), all packets from that station will be delivered to any IGate port that has "seen" the station.  Also, any messages addressed to such stations will also be delivered.  This is done so that the IGate can deliver its required functionality.

Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32