It seems that you have used an incorrect umask setting while you have started the smsd.
I checked this with 3.0.2, and as Debian has not made any changes to the C code, this is not a Debian problem. The smsd inherits umask value from the calling process. This value limits permissions placed on newly created files. With umask value 0 no permissions are limited. When the smsd moves files between directories, it reads the source file and creates a new file for destination. This is because some directories can be located on different disks or over the network. The new file is created using the same permissions than the source files has. If the source file has rw-rw-r-- and umask is 022, permission is limited to rw-r--r--. In your case it seems that umask 066 was used. Please check this. Regards, Keke