The problem with the subjunctive mood in French is that it really only has two tenses: subjonctif présent and subjonctif passé. The indicative mood has a whole slew of tenses (I count 8!), ranging from plus-que-parfait all the way to futur parfait. In theory there are all those tenses available also in the subjunctive mood, but they have fallen out of use. So one has to make do with only two tenses in the subjunctive mood. That's why the temporal match is a bit loose. The "rule" being that unless you want to draw specific attention to the temporal aspect, you simply go with the present subjunctive.