Damage will only happen if you can see it, if you have purple, green, red, corners...or any discoloration when you should see all white screen (for example) then there is a problem..............if you see nothing then nothing is wrong.
I have a Sony 34 XBR WEGA CRT unit and at one point had my mains flanking the unit which have 3 10' Woofers and are NOT sheilded, at 18 inches from TV I had no issue, anything closer and I could see the effects of the magnets easy.