VPN P2P: delete IPsec phase 1 & install IPsec SA, tunnel down +-50 minutes each day

Hi,

I have a P2P VPN that sometimes goes down for 40-60 minutes once or twice a day. The tunnel itself doesn't go down, but no traffic is passing. In the logs I see a delete IPsec phase 1 SA followed by install IPsec SA 45 min later, which correlates with the outage. What does the delete & install messages exactly mean? Is this a standard renegotiation because of key time?

Thanks