Hi,
I was suspecting RE failover having looked at the logs but judging from the Master and backup RE uptime, it doesn't seem so, assuming the node that came up first was master [i.e Member 1]. You might also try logging on the backup RE and check for any logs as well as core dumps if any.
The load averages appear to be normal.
I would suggest to open a JTAC case for RCA, if you have not done so already.
Cheers,
Ashvin