inconsistent parsing for time with numbers

this one is just wrong
```bash
$ curl -s -XPOST http://0.0.0.0:8000/parse --data "text=the second sunday of October last year" | jq .
[
{
"dim": "time",
"body": "the second sunday of October last year",
"value": "{\"values\":[],\"value\":\"2016-10-02T00:00:00.000-07:00\",\"grain\":\"day\",\"type\":\"value\"}",
"start": 0,
"end": 38
}
]
```

this one gets both parts right, but why did just changing the one word change so much of the parsing?
```bash
$ curl -s -XPOST http://0.0.0.0:8000/parse --data "text=the second thursday of October last year" | jq .
[
{
"dim": "time",
"body": "the second thursday of October",
"value": "{\"values\":[{\"value\":\"2017-10-12T00:00:00.000-07:00\",\"grain\":\"day\",\"type\":\"value\"}],\"value\":\"2017-10-12T00:00:00.000-07:00\",\"grain\":\"day\",\"type\":\"value\"}",
"start": 0,
"end": 30
},
{
"dim": "time",
"body": "thursday of October last year",
"value": "{\"values\":[],\"value\":\"2016-10-06T00:00:00.000-07:00\",\"grain\":\"day\",\"type\":\"value\"}",
"start": 11,
"end": 40
}
]
```