Over the past two decades I've noticed warning signs about mountain lions at National Forest/Parks trailheads.
A ranger I asked told me it was for liability issues---if a cougar caused injury, consider yourself forewarned.
Personally. I've only seen one mountain lion in the wild and heard local accounts of only a couple more.
Not too terribly concerning really, but then over the past two years there have been quite a few in urban coastal areas,
Then this goes viral:

Be careful out there!