transmission question

[n00b on demand]

My car runs very smoothly while running in 3. I cant remember who said it to me before but someone said that its not bad for our engines to rev out. But as i have said before i never let it stay above 3,000 rpms. I only use 4th on the highway or on a very long straight away. Does the TC lock up on every SVX? Does this happen to any other car? Ive always wondered because the TC locking up is one of the weirdest things ive had while driving a car...never seen it in any other car and im young but ive driven alottttt of other cars.