Overnight I noticed two instances of port==0 simultaneously in the X-Node and Chat headers.

My code to detect this situation has been active for a long time, but this is the first time it's ever gone off.

GET /uri-res/N2R?urn:sha1:___LALX23OVKIH3QUUPM4OVG6RFOZ2OQ HTTP/1.1
HOST: N.N.N.N:6412
User-Agent: LimeWire/4.0.2
X-Queue: 0.1
X-Gnutella-Content-URN: urn:sha1:___LALX23OVKIH3QUUPM4OVG6RFOZ2OQ
X-Alt: A.A.A.A
X-NAlt: B.B.B.B
Range: bytes=999930-1099939
X-Node: X.X.X.X:0
Chat: X.X.X.X:0
X-Features: chat/0.1, queue/0.1, browse/1.0

Did you notice this on two different uploaders, or just one? (And does it happen very often?)

I noticed it on two different servers. I did not notice whether the client was the same.

I have set breakpoints, so I can tell you when I see it again.