That is the sign of active yeast! What is the ambient temp of that room?
Two cheap things to pick up on our host’s site for your next brew (that will last your next several brews!)
-temp strips
-fermcap
To your question, I would not worry too much about the blowoff, but to put your mind at ease, pick up a $0.75 spray bottle, mix up some sanitizer (I prefer Star-san because its no-rinse) in it, and keep it on hand (it will usually last a month or so once mixed, and retain its sanitizing, bacteria-killing pH). Take the stopper and airlock out, rinse it well, spray/spot-sanitize the mouth of the carboy and the airlock/stopper, wait 60 seconds, and put everything back in place.
Next time, u can either use fermcap to prevent that level of krausen or use a blowoff tube instead of the airlock (just google them).
Get a blowoff tube on that thing! But yeah, definitely clean out the air lock. If that clogs too much, the top will blow off and you’ll have quite a mess to clean up. It’s happened to me 2x and I have the stains to prove it :lol:
Yeah, if you are plugging up the airlock, it is only a matter of time before she blows. At a minimum, take it out and clean it up and replace with foil until it slows down a bit.