If the headlights flash on/off when you start your car after you change the battery, is something wrong?

My mom just changed her car battery and everything seemed fine until she tried to start it. The headlights kept flashing, so she%26#039;s worried she might have done something wrong. Somebody please shed some light on this for me. Btw her car is a %26#039;95 Nissan Quest.|||it is a grounding problem just clean the battery terminals and tighten them down all should be well after that.|||clean the terminals or just wiggle them back a forth a few times them tighten them, them the car will start