Single-clove garlic

[winterfly]

I planted my garlic around Sept 15 last year and harvested it around June 5 this year. About one fourth of my harvested garlic is single clove, and one bulb seems to have only two cloves. I have never had any single clove garlic in the past. I only planted hard neck garlic and pulled the scapes about 3 weeks before harvest. The plants were about one fourth dead when I harvested. I did some research and didn't get any clear answers. One possible answer is the mild winter we had. Anyone have any similar experience?