Private message error in v5.2.5

[Craig]

I have a user that gets this message when selecting a message in the private messages;

{"errors":[["birthdayfield_nonprofile_tab"]]}

Immediately after the "real" message is displayed for a second, then the above error is shown.

[Craig]

This is resolved.

Strangely enough, the user did not have his date of birth in his profile. Once he added it he is able to read his private messages.

I am not sure if this is a bug, or built by design. Odd though.