Classic problem, one of the mater locks, ie either front door has a sticky/sluggish motor mechanism, so one lock opens fully one doesn't open fully, nearly but not quite, when the pulse for open stops it leaves one lock saying it should be locked, so they relock, easiest way to find which is disconnect each door lock electrical supply at a time and see which one immediately relocks upon pressing unlock.
You will most likely be able to free off the mechanism, could be part of the linkage, the grease they use can attract dust dirt grit etc causing the sticky action, rarely a lock fault itself, almost always the linkages etc.
tabetha