You caught the system at a bad time. Tag edits have to be approved by a couple users. You have the rep to suggest edits but not to approve them. In between the time an edit is suggested by anybody and such a time as it is either approved or rejected by a mod or a couple higher rep users, editing is locked for that tag.
The "edit pending" message was for real. Somebody had, minutes before, proposed an edit to that tag and it was pending approval. I approved it a few minutes back, so now anyone is free to edit again—hence you see something different now.