Sequencing issues aside, just because there was less than a 3nm radar standard doesn't mean there was no separation.
3nm by radar is intended to achieve at least 1nm in reality (which means you can be just 1nm from another aircraft if a procedural standard was applied (eg 1 north of, and the other 1nm south of, a line feature etc).
In your case, separation was more likely achieved visually (by the TWR, by the military pilots having you in sight and maintaining their own sep etc - they do make a living out of sighting and not crashing into other acft after all, although they do usually shoot them out of the sky....
)
And yes, I have worked DN APP (loved it!), but, alas, am no longer there so don't know the particulars of this case. If you are truly concerned, you should ASOR/ESIR it.