Is It Me or the Airbrush?!

OK, getting past the loaded question here's my situation...

I'm painting the standard 3-color NATO camoflage on a Revell Marder 1 A3. I've got the base color (Tamiya XF-67) painted a couple weeks ago. Last night I used my trusty Badger 350 with a fine tip to put on the black (Tamiya XF-69). It went on perfectly. I then cleaned my airbrush to near perfection.

This morning I went out to paint the brown (Tamiya XF-68) and the airbrush wouldn't cooperate. Hardly any paint would come out and when it did it looked like it was dry the second it hit the model surface. The temperature in the garage where I was painting was probably in the low 90s. I even thinned the paint a little more that I usually like adding a little more rubbing alcohol than I normally use. I finally ended up putting my medium tip on and hitting the model with quick pulses. It didn't give me quite as fine a lines as I wanted but I figure I can go back an cut in with some of the green or black later.

Is the problem the airbrush, the operator or was the weather perhaps a bit too warm? This is the first time I've had a problem applying a camo pattern to a vehicle.