The main risk with a short mast is that your feeder cables may come in contact with your roof, particularly at the edges, or other roof fixtures. (What is that metal rod in front of it -- maybe an antenna?)
Because the cable is flexible, it can move during a windstorm. Over the years, if it is rubbing against your roof, the insulation can wear down and you risk electrifying parts of your house or reducing the reliability of your electric service. Worst case, the cables could arc and cause a fire.
Adjusting the length may be a simple operation but to do it safely requires shutting off power before that point, which you'd need the utility to handle. Additionally, further work may be required if, say, the wire leading down to your meter or service panel was not long enough to simply extend the current mast in place.
I'd recommend calling your electric utility to come check it out. They will tell you what the safety concerns and current codes are, and may even be able to correct the problem. For the work on/in your home, you may need an electrician, depending on your state, and will almost certainly need a permit.