Not an immediate emergency, but you need to take action. This is probably your secondary drain as your primary us clogged. Find your inside unit in attic or closet and check the pan for standing, cold water. If so, you'll see a primary drain with probably a white PVC T. That's drain needs to be blown out. Tackle if you want or call AC company in the morning.
The primary might run to a nearby bathroom, check for 2nd p trap under sink, or it may run outside too. See if you can determine if it's your primary or secondary that is dripping.