Excessive DNS lookups for slack.com

[buholzer]

Looks like the Octoslack plugin is looking up the slack.com DNS name around twice a second.
Any idea why that is?

17:15:24: query[A] slack.com from 192.168.1.22
17:15:24: cached slack.com is 54.203.112.76
17:15:24: query[AAAA] slack.com from 192.168.1.22
17:15:24: cached slack.com is NODATA-IPv6
17:15:25: query[A] slack.com from 192.168.1.22
17:15:25: cached slack.com is 54.203.112.76
17:15:25: query[AAAA] slack.com from 192.168.1.22
17:15:25: cached slack.com is NODATA-IPv6
17:15:30: query[A] slack.com from 192.168.1.22
17:15:30: cached slack.com is 54.203.112.76
17:15:30: query[AAAA] slack.com from 192.168.1.22
17:15:30: forwarded slack.com to 1.0.0.1
17:15:30: reply slack.com is NODATA-IPv6
17:15:35: query[A] slack.com from 192.168.1.22
17:15:35: cached slack.com is 54.203.112.76
17:15:35: query[AAAA] slack.com from 192.168.1.22
17:15:35: cached slack.com is NODATA-IPv6
17:15:36: query[A] slack.com from 192.168.1.22
17:15:36: cached slack.com is 54.203.112.76
17:15:36: query[AAAA] slack.com from 192.168.1.22
17:15:36: cached slack.com is NODATA-IPv6
17:15:41: query[A] slack.com from 192.168.1.22
17:15:41: cached slack.com is 54.203.112.76
17:15:41: query[AAAA] slack.com from 192.168.1.22
17:15:41: cached slack.com is NODATA-IPv6
17:15:47: query[A] slack.com from 192.168.1.22
17:15:47: cached slack.com is 54.203.112.76
17:15:47: query[AAAA] slack.com from 192.168.1.22
17:15:47: cached slack.com is NODATA-IPv6
17:15:47: query[A] slack.com from 192.168.1.22
17:15:47: cached slack.com is 54.203.112.76
17:15:47: query[AAAA] slack.com from 192.168.1.22
17:15:47: cached slack.com is NODATA-IPv6