I tried to change my display name just moments ago, and I got the error:

Display name may only be changed once every 30 days; you may change again on Apr 11 at 3:54

I have never changed my account display name. Looking back, I did start an account on the UX StackExchange 3 days ago (with no activity so far), which could be what is triggering the message. If that's the case - is this by design? If it is, I think that the error message should be more clear. If not, any idea what the problem is?