Warnings in log after new bootstrap

I have a 4 node cluster (3 nodes running with Ubuntu 12.04 and 1 with Ubuntu 14.04), each of them with the lastest software versions.

After a new bootstrap my error.log file on all four servers is getting entries that did not happen before.

2014-11-30 13:20:58 28579 [Warning] WSREP: Failed to report last committed 208532168, -4 (Interrupted system call)

And this is happening every other minute, the configuration files nor the data files have been changed, the database and the software that uses it is the same and has not been changed.

What can I do?