And now I got this:

Message from syslogd@banana at Jun 2 03:53:01 ...
kernel:[ 2400.804032] [Hardware Error]: Corrected error, no action required.

Message from syslogd@banana at Jun 2 03:53:01 ...
kernel:[ 2400.804074] [Hardware Error]: CPU:1 (f:5:8) MC4_STATUS[-|CE|-|-|AddrV|CECC]: 0x94044001ca080813

Message from syslogd@banana at Jun 2 03:53:01 ...
kernel:[ 2400.804115] [Hardware Error]: MC4_ADDR: 0x00000001592ebf40

Message from syslogd@banana at Jun 2 03:53:01 ...
kernel:[ 2400.804139] [Hardware Error]: MC4 Error (node 1): DRAM ECC error detected on the NB.

Message from syslogd@banana at Jun 2 03:53:01 ...
kernel:[ 2400.804192] [Hardware Error]: cache level: L3/GEN, mem/io: MEM, mem-tx: RD, part-proc: SRC (no timeout)

Hmmm!