I'm resetting a filter with a date literal and it suddenly became... AMBIGUOUS!

The date was entered in unambiguous format, so the expression would be:
cNewFilter = "aDate = {^2000-03-28}"
SET FILTER TO &cNewFilter

Later, the code saves the filter in a variable and uses another filter.
cFormerlyNewFilter = SET ("FILTER")

When the code attempts to restore the filter:

cFormerlyNewFilter equals "ADATE = {3/28/2000}"

Since we're running STRICTDATE at 1, we get an error message.

Anyone have insight into this?