Asterisk - registration timeout

Over the last few days I have noticed registration timeouts for about 30 mins at 4 AM PST. Can someone else confirm this ? My registration interval is 260 seconds. All other trunks are OK.

[Jan 6 04:04:21] NOTICE[9619] chan_sip.c: -- Registration for 'xxx@sip.voipwelcome.com' timed out, trying again (Attempt #1)
[Jan 6 04:04:41] NOTICE[9619] chan_sip.c: -- Registration for 'xxx@sip.voipwelcome.com' timed out, trying again (Attempt #2)

Trunk Settings,

disallow=all
allow=ulaw
fromdomain=codeblue.voipo.com
host=sip.voipwelcome.com
insecure=port,invite
nat=yes
secret=xxx
qualify=no
type=peer
username=xxx
canreinvite=no
session-timers=accept
session-refresher=uac