Asking Tenants to Help Foot the Bill?

Let me begin by saying that I believe I am a very fair landlord. I respect my tenant's privacy and take care of tenant concerns when they come up. I will also say, the tenants in this property do not complain too much about repairs and such...there have been few repair issues since they have lived there, but part of this may be that they simply have not told me about everything. I will also say, one of the tenants in this property is my brother and true to form, he takes advantage of that, paying his rent late every month and just generally making it hard for me to manage the property as I would with most tenants. With that said, two weeks ago (the Friday before the 4th of July weekend), I got a call from him that his power was out. My power was actually out that day at my house, and it was quite hot out which made it especially troubling. Power seemed to be down throughout my city, and I had already called the power company for my own place so I knew that. When my bother told me his power was out, I explained the outage to him, but he was sure his was not an outage bcs only half his lights and outlets were out. The power company had not given him a definitive answer as well. As we were talking the upper tenant called to say the same. Mind you it is Friday night before a holiday...long story short, both of them were so insistent it was not an outage, that I paid an off duty electrician to come by a a higher rate to check it out. He was in and out in about 5 minutes and charged me to reiterate that it was an outage. My brother made the check out to him and contacted today (the day that he paid his July rent!) to ask about reimbursement. I mentioned that I felt him and the upper tenant should shoulder some of the cost bcs I had told them it was an outage but they insisted on an electrician. He was livid. I have not spoken to the other one yet...is this worth the hle or should I just suck it up and pay for it?