When i get up in the morning and lean my head back and gargle with listerine, i spit out a brownish flem, does this mean i'm infected.?

Phlegm: Most often phlegm that is deeper green and brown are indicative of an infection. It could be respiratory or a sinus infection. Some of these situations require an antibiotic for a speedy recovery. You should consult with a physician.

Coffee drinker?: It's fairly normal for a bit of mucous (phlegm) to accumulate deep in the throat during the night. If you're a coffee drinker and like to consume your morning cup of joe prior to your listerine, it can 'stain' that brown. The heat from the coffee can loosen it up making it easier to come up when you gargle, but it'll still be brown.