What happens if you don't move the caliper piston back into position?

I changed my breaks, half way into it my sister calls asking if I am going to pick her up. So I rushed and never pushed the caliper piston back for the new breaks oh and I also didn't flush the break fluid. It has been five months now and other then squeaky breaks (normal so I hear) every now and then I have not had any problems. oh and it is normal when you break fast for the car to skid forward before it stops (I didn't notice the light change red, didn't want to get a ticket in the mail). This is my first car and I am learning as I go along.