Suggested edit approval rules were revised few months ago and now require a majority of 2 votes to be approved/rejected.
The edit on How to convert PDF to Microsoft Word 2007-format ? was approved by you & needed another approval vote to be vetted & passed through, which I have done now & hence is accepted.
The other suggested edit was already approved by one user and needed a secondary approval vote for it to be accepted, and since yours was the second approval vote, the edit got accepted when you clicked approve.
So yes this is a feature, not a bug.