I agree with Mike, there is probably some weird data regarding this particular name, as opposed to something wrong with Mendix.
Try inspecting your database and check for non-standard characters invisible control characters tabs etc.
Any chance there is more than one space between his first and last name in the FullName attribute?
You were right, someone put an extra space after the first name. Is it best practice to have a "Trim" in a BCo event on these types of attributes?