curved lines and arrowheads

[Steve Easterbrook]

I've noticed what looks like a bug in how arrowheads interact with 
curved lines, especially if the anchor points are close to the 
arrowhead. The problem shows up on this simple graffle diagram:
http://www.cs.toronto.edu/~sme/pub/strange.graffle
http://www.cs.toronto.edu/~sme/pub/strange.pdf

I've included a pdf too, in case it's just my version of graffle that 
does this (3.1.2v70). I get the same results with other arrowheads. 
Looks like the curve drawing algorithm starts out 180 degrees in the 
wrong direction from the arrowhead.
Is this a known bug? Or am I missing something in the settings?

Steve