I don't see anything else in /var/log/messages.
I ran journalctl --follow /usr/libexec/ipa/ipa-otpd, and it shows the otpd service
successfully authenticating a user and then shutting down.
bind end: success
response sent: Access-Accept
Socket closed, shutting down...
Socket closed, shutting down...
Any way I can enable more verbose logging for this service?