Yes this appears to be a bug in AEM 6.2. And the docs says, its fixed with an FP for 6.2 and won't be seen in 6.3.
My point is it is still an issue in 6.3. As Laura mentioned, Adobe has to investigate to see if it was ever fixed in any AEM version and do the needful. I totally understand, unlocking the page prior to publishing it will solve the problem. But in the first place, AEM should not allow publish action when a page is locked is what I believe.