JKR mistake in World Book Day chat?

[Haggridd]

No: HPFGUIDX 95068

I haven't seen this adddressed elsewhere.  JKR said that Charlie was 
two years older than Percy.  Were that the case, in PS/SS, Charlie 
would have been a seventh-year at Hogwarts and captain of the 
Gryffindor Quidditch team, not Oliver Wood.  Percy was a fifth-year 
prefect.  Is my arithmetic off? Does anyody else have any thoughts 
on this?


Haggridd