Error while flagging : Your message must be longer than 10 characters
Today I found a question in Stack Overflow that was helpful in resolving a server administration issue. The question was closed as "off-topic" for Stack Overflow. I felt that the helpfulness of the question meant that it merited review for a move to Super User, and so attempted my first "flag" of a question. I selected "it needs moderator attention: other", and entered a description that summarized the above.
When the description is less than 10 characters long, the message below the input box indicates "n characters to go". When 10 characters entered, the message switches to "490 characters to go". My description resulted in a message of "308 characters left". When I press the "Flag Question" button, the flag dialog closes and the following text occurs in an orange box: "Your message must be longer than 10 characters" and the flag operation failed (as the number of flags I can place has not changed).
Is this a bug, or is there some nuance of flagging that I have missed?