Is there an omen to finding a dead cat on your door step?

over the past 3 months, when coming home after working all night, there have been 3 stray newborn kittens that frequently sleep on my doorstep, laying on top of my doormat. this morning it was very cold and i found one of the kittens dead on my doorstep. I think it died of hypothermia, is this an omen or just a stray cat using my doormat as a home and dieing of hypothermia?