[R] "lag1.plot {astsa}" vs. "lag.plot {stats}"

[Paul Domaskis]

I'm following http://www.stat.pitt.edu/stoffer/tsa3/R_toot.htm to ramp
up on both time series and R.  About 40% of the way down, the tutorial
uses lag1.plot from astsa and lag.plot from stats.  The positioning of
the dots look different between the two.  Nothing jumps out at me from
the help pages that explains why they would be different.  Can anyone
confirm this difference, and hopefully suggest explanations?