Deed restrictions write up?

We live in a neighborhood that has deed restrictions and an HOA. I don't mind it, but recently is started working nights and my wife works days. We have'n't had a chance to mow our lawn in a couple weeks, it is a bit grown up but it's not really that bad. Although aparently there has been a complaint or 2. The thing is today someone stopped by to tell me about it, and said he decided to tell me instead of having me written up as we are new in the neighborhood. I did know about the restrictions, and i've been trying not to break them at all, this is the first time this has happened and there really isn't much i can do. I'm going to mow it tomarrow, i don't mind mowing the grass. I'm just curious really what all can they do? I mean whay exactly does it mean when an HOA writes you up?