Chances are that you were on the active tab rather than the newest tab. A highlighted question normally means it has one or more of your favourite tags rather than indicating it is new.

There is an automated process that randomly bumps unanswered questions as 'active' in order to help get them attention. If this happens then in the list of questions the last activity is shown as having come from community but when you click through to the actual question page nothing is shown in the log as it's not a real edit.

It's also possible that there was a spam answer submitted and it was removed by the time you viewed the question.

It is possible that there was either a spam post or "me too" answer submitted and it was removed by the time you viewed the question. It is not at all uncommon for questions to be wrongly resurrected that way but the review queue normally sorts them out quite quickly.