Minor depression is more common than many people believe and doesn't make your medical record questionable, in my opinion. The following is my own experience and should not be considered health/legal advice.
I went to the doc 4 years ago for symptoms of depression such as sluggishness and lack of motivation (though I never had any thoughts of self-harm or harm to others). He put me on meds and sent me out the door but they seemed to dull my mental sharpness. With his permission I stopped the meds and adjusted my lifestyle to include more outdoor activity, rigorous exercise, less alcohol, more water and better food, felt better than ever not long after. Two months later I went back, was declared "cured" and have been feelin' good ever since. Something tells me lifestyle choices were the problem in the first place.
Considering it had been over three years since I was declared healthy by a licensed medical professional I felt comfortable checking "NO" on that question on the PAL and received my card no problem.
That being said, your situation may be different, and in general, honesty is the best policy when dealing with the federalies.