Can magnets permanently damage CRTs?

I have a 1978 RCA XL-100 TV that I use in my main HT system. It's obviously a CRT and it's solid state. Without naming names, I'll just say that a demonstration of a magnet's effect on the picture tube was performed. Now the picture remains distorted even though the magnet is far away from the TV.
My question is whether the magnet just temporarily affected the CRT's stability or is the CRT ruined?