Dr. said aging & habits can shift bottom front teeth a bit. what habits cause that? i clenched teeth 3 times while stressed. did those few times do it

Complex answer: Tongue thrust habit may cause your posterior teeth to move forward thus shifting your anterior teeth. Over a long period of time, a collapse of your vertical dimension due to grinding down of your posterior teeth can cause the lower anteriors to shift as they are pressed into the linguals of your maxillary anteriors. Your dentist will need to explain this further.