Superevent t_0 is not always getting updated when preferred event changes

The t_0 of the superevent is commonly interpreted as the time of the GW event, but I noticed that it does not necessarily get updated when the preferred event changes. For example, S230601bf has t_0 = 1369694512.096006 (see the REST API output) but its preferred event, G409183, has gpstime = 1369694512.101074 . The previous preferred event, G409181, had t_0 = 1369694512.096006 so that's where the superevent's t_0 came from, evidently. Note that the superevent's t_0 DID get updated when the preferred event changed from G409180 to G409181, but DID NOT get updated when it changed from G409181 to G409183.