Kaiser,
That is probably because North Americans like to score better at Scrabble When playing in English, we often get stuck with the 'Z's, the least-used letter in the English language.
First time I have seen this too.
Browsers: Safari 5.0.3 (7533.19.4) and Firefox 3.6.13 (Firefox loaded after fault seen, for test purposes)
Both posted via QR with gap of several minutes and other posts, and edit first attempted without reload but subsequent attempts all after reloads.
I would...
XenForo 1.0.0 Release Candidate 1
Not encountered before today but I made two consecutive posts to a thread, then wished to edit the second of them. On clicking 'Edit' in the second post......... the first was opened for editing.
Thinking that I may have made a silly mistake, I cancelled...