Impatient warm standby - Recovery spam in pg_log/startup.log

We're doing a basic WAL shipping replication setup. Our Primary server ships WALs via SCP to the Warm Standby every five minutes. We did the base backup, and brought Warm Standby online. The server ran through all WALs available, but now is spamming the startup_log with requests for the next WAL, which hasn't even been generated yet! Is this expected behavior? If not, how can we stop it?

cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000042': No such file or directory
LOG: restored log file "000000010000001300000042" from archive
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory
cp: cannot stat `/home/ubuntu/wals/000000010000001300000043': No such file or directory

Thanks!