My trunk keeps popping open by itself. The battery was replaced last month on 2010 BMW 528i

As I close the trunk, I can here the latch engage and feel a click prior to closing, as if something is triggering it to release. It will stay closed for about 4 seconds then release as if I had pressed the release button. This happens when the car is in park, drive, reverse and even when the key is off. However, after everything is off, it will stay closed.

Asked by for the 2010 BMW 528i
should be under factory warranty