More opinion than anything....
Any time you perform services professionally for another and get paid, regardless of how often or large the service may be, it's wise to protect personal assets from legal troubles the business may present.
An LLC means if you were to damage someones property, they could not sue you into personal bankruptcy, take your home, etc. If managed correctly, the only liability would be to the business and its assets and your personal assets would not be at risk. In addition, you may be able to use a Schedule C when tax filing to get business deductions regarding the equipment you use for business.
Whether or not an LLC is right for you can really only be determined by discussing it with an attorney, which you may also need to file the LLC inception forms.
Basically.... this isn't a question for freelancers, it's a question for an attorney. If you are concernsconcerned, it's well worth it oto pay for an hour of consultation services with an attorney. A couple hundred dollars (or whatever) now may save you many headaches in the future.