i stepped on my brake pedal and it went down a little more then usual

Possible small leak has started and you are losing pressure somewhere. Need to locate leak. Other possibility is master cylinder is starting to fail. Check for small leak first. Check fluid level.

if you cant find a leak try adjusting rear brakes

#2 , to start. Assuming it's a DX-4Cyl. with rear drums. Observation to make , if it is drum--- does your parking brake pull up higher than it used to? Again lots of assuming here, but if that's the case , than be sure to clean and adjust the brake shoes properly FIRST before adjusting the parking brake(which most likely will not be necessary after shoe adjustment). ----------If it's not drum in the rear , then see answer #1 (and I'll just say DUH.)