Child support question

I'm kinda new to this so I'm still figuring everything out. A little back round. My ex husband and I were together for 3 years married just under 2 years when I found out he had been cheating on me since we were engaged. So I took our son and left. At the beginning I tried really hard to get him to be in my sons life and well he's only seen him twice since September. But he started paying child support recently which is a huge help! And relieves a lot of financial stress off of me. He's only paid one month and is late this month without saying anything about it. Do I ask him to pay it or just leave it alone?