zip_distance with vectors not returning correct order of results

Using the example given in the README:
#> zipcode_a zipcode_b distance
#> 1 08731 08901 6.9
#> 2 08734 08005 45.1`

You can check a map to verify that the distances for the two pairs of zipcodes is swapped. 08731 > 08901 is actually 45mi, while 08734 > 08005 is 7mi.

You can see it more distinctly using the same repeated values:
zip_distance( zipcode_a = c('08731', '08731'), zipcode_b = c('08731', '08005') )

zipcode_a zipcode_b distance
08731 08731 6.9
08731 08005 0.0

They are also in the wrong order for multiple rows n > 2.