They seemed to have been generated between 94 and 684 seconds, notifying of other_commenter, mostly toward the latter time frame. Why they would be continue to be generated over 11 minutes later is a little bizarre.
This functionality is a core part of (apparently last updated XF 2.1.0 RC 3 according to the templates), rather than part of any add-on, so it probably represents some bug in the system. I'm not sure we can reasonably do anything besides maybe pass it on to XF devs.