“few seconds ago" and "a minute ago” text mismatches with the actual time given

[Krishna-Hari]

Hi,
The text being displayed for "am-time-ago" directive like "few seconds ago, a minute ago" for the given time is not matching.
Some times the text changes before "few seconds" and some times it changes after "few seconds" than the exact time.

Here is the plunker which reflects the issue mentioned.
http://plnkr.co/edit/FiKrOed8YJu6OV8fNd8k?p=preview.

Please consider this on priority as I am facing this issue in production.
Thanks