g1.types doesn't detect dates

As per g1.types docs, column d should have been date but it detected as string. Would like to detect below as date.

var data = [
  {a: 1, b: 1.1, c: 'c', d: '2014-04-04', e: true},
  {a: 2, b: 2},
]

g1.types(data)
{a: "number", b: "number", c: "string", d: "string", e: "boolean"}

Although, this works with options = {convert: true}

g1.types(data, {convert: true})
{a: "number", b: "number", c: "string", d: "date", e: "boolean"}

If this is intended, please update the documentation?