Hi,

The sys_admin capability is very powerful so it should net be required. Do you know at which condition the request has been made?
Has something changed in the services recently or is it a result of a configuration change?
To investigate further, you can enable full auditing in the audit daemon:

1) Open the /etc/audit/rules.d/audit.rules file in an editor.
2) Remove the following line if it exists:
-a task,never
3) Add the following line to the end of the file:
-w /etc/shadow -p w
4) Restart the audit daemon:
  # service auditd restart
5) Re-run your scenario or wait for the nightly job to run.
6) Collect AVC denials:

  # ausearch -i -m avc,user_avc,selinux_err,user_selinux_err -ts today

refer to capabilities(7):
       CAP_SYS_ADMIN
              Note: this capability is overloaded; see Notes to kernel developers, below.

              * Perform  a  range  of  system administration operations including: quotactl(2),
                mount(2), umount(2), pivot_root(2), swapon(2), swapoff(2), sethostname(2),  and
                setdomainname(2);
              * perform  privileged syslog(2) operations (since Linux 2.6.37, CAP_SYSLOG should
                be used to permit such operations);
              * perform VM86_REQUEST_IRQ vm86(2) command;
              * perform IPC_SET and IPC_RMID operations on arbitrary System V IPC objects;
              * override RLIMIT_NPROC resource limit;
              * perform operations on trusted and security Extended Attributes (see xattr(7));
              * use lookup_dcookie(2);
              * use  ioprio_set(2)  to  assign  IOPRIO_CLASS_RT  and  (before   Linux   2.6.25)
                IOPRIO_CLASS_IDLE I/O scheduling classes;
              * forge PID when passing socket credentials via UNIX domain sockets;
              * exceed  /proc/sys/fs/file-max,  the  system-wide  limit  on  the number of open
                files, in system calls that open files (e.g.,  accept(2),  execve(2),  open(2),
                pipe(2));
              * employ  CLONE_*  flags  that create new namespaces with clone(2) and unshare(2)
                (but, since Linux 3.8, creating user namespaces does not require  any  capabil‐
                ity);
              * call perf_event_open(2);
              * access privileged perf event information;
              * call setns(2) (requires CAP_SYS_ADMIN in the target namespace);
              * call fanotify_init(2);
              * call bpf(2);
              * perform privileged KEYCTL_CHOWN and KEYCTL_SETPERM keyctl(2) operations;
              * perform madvise(2) MADV_HWPOISON operation;
              * employ the TIOCSTI ioctl(2) to insert characters into the input queue of a ter‐
                minal other than the caller's controlling terminal;
              * employ the obsolete nfsservctl(2) system call;
              * employ the obsolete bdflush(2) system call;
              * perform various privileged block-device ioctl(2) operations;
              * perform various privileged filesystem ioctl(2) operations;
              * perform privileged ioctl(2) operations on  the  /dev/random  device  (see  ran‐
                dom(4));
              * install a seccomp(2) filter without first having to set the no_new_privs thread
                attribute;
              * modify allow/deny rules for device control groups;
              * employ the ptrace(2) PTRACE_SECCOMP_GET_FILTER operation to dump tracee's  sec‐
                comp filters;
              * employ  the  ptrace(2) PTRACE_SETOPTIONS operation to suspend the tracee's sec‐
                comp protections (i.e., the PTRACE_O_SUSPEND_SECCOMP flag);
              * perform administrative operations on many device drivers.

Whatever caused this I have not been able to reproduce it since so I'm just closing this as NOTABUG.