Ours is more like 30 miliseconds!
I just got my Eos last week and have not had any trunk problems as if yet. Re above, the manual on page 34 (US edition booklet 3.1) says the doors/trunk relock after 30 seconds. It's suppose to be a safety feature.
If the above is correct AND you're not getting your full 30 seconds, it sounds like it may be a timer problem.