plot() with TukeyHSD

Hello,

When plotting the results of a TukeyHSD multiple comparisons
procedure with an ANOVA (lm) object, an extra line appears
in the confidence intervals that contain 0.  For example (this
is straight from the TukeyHSD helpfile):

summary(fm1 <- aov(breaks ~ wool + tension, data = warpbreaks))
TukeyHSD(fm1, "tension", ordered = TRUE)
plot(TukeyHSD(fm1, "tension"))

An extra line segment appears in the interval to the right of the 
dotted zero line.  Coincidentally, if all of the calculated 
intervals for a dataset don't contain zero, this isn't a problem 
-- so I guess the line segment "belongs" to the zero line.  I
checked R Search and didn't find this mentioned before... but
please let me know if I overlooked something.

Jason

R 2.2.0 on Windows 
-- BTW, the error didn't happen on my Mac OSX w/ R 1.9.1

--
Assistant Professor of Statistics
Mathematics and Computer Science Department
University of Richmond, Virginia 23173
(804) 289-8081   fax:(804) 287-6664
http://www.mathcs.richmond.edu/~wowen

"This is R. There is no if. Only how."
Simon (Yoda) Blomberg