Whilst not being able to tell you for certain that you didnt experience a loss of seperation I would suggest that the fact you did not discern any tcas manoeuvre to avoid makes it sound unlikely.
I think it is always particularly difficult for people not used to it to judge the 1,000 ft vertical seperation, use of the word thousand makes it sound like a large distance but it is not. The best way to imagine it using everyday experience is to imagine a motorway junction. Before reaching the turn off you have the blue and white countdown markers (300m,200m,100m). From the 300m marker to the turn off is roughly 1000ft. Now imagine a 747 at the 300m board and an A380 at the turn off and Im sure youll agree you could easily make out the markings on each aircraft.
Alternatively just think Usain Bolt can run that distance in less than 30 Seconds!