I have a 2008, my question is, is it normal for the headlights to flicker eveytime you press the brakes?

no it is not at all there are multiple possibilities of the cause one could be a loose connection that moves around as you brake another answer could be a defective alternator or any sort of bad ground or short in the headlight circut

I replaced mine and found that my 08 the high beams were lose banging around in the socket. they still worked fine but did not trust them. also check the battery term. dont know why but they get lose.

Bad battery terminal connection...mine did this for the first 40K that I drove it. i tinked with it endlessly, then one day it just stopped.

I call those electrical demons - seemingly random electrical issues. At one point every time I turned right my stereo turned off and on again. These things just happen sometimes. It may very well go away on it's own (mine did). But check the wires for any loose or dirty connections and check all your ground connections. Bad ground connections can make the strangest things happen.