buggy screen or normal???

Is it to be expected for a screen to act buggy. My new droid's screen sometimes doesn't "turn on", ie when I'm ending a call and pull the phone away from my ear, it won't always turn on so that I can access the screen. Is this type of glitchy inability to switch back and forth a common occurrence with these kinds of screens? Or should I replace the phone..this has happened 7 times in two weeks. The only way around this has been to slide open the phone manually ,,,,,,,,,or is there a setting that always keeps the screen on?

Thx