Tree trimmers for utility companies generally work year-round, trimming trees pre-emptively, and responding to storm emergencies. They don't take a lot of time off. So to answer your question, they do prune trees in the spring and fall, (as well as winter and summer). There's a lot of work to be done, and they need to work year-round to get it done. So you may just be seeing them in your neighborhood now, but that doesn't mean they weren't working prior to that, they were just in a different area.
Your neighborhood just happened to be on the list for work at this time.
There are different schools of thought on when is the best time to prune trees, but many arborists, including myself, feel that the time of year trees are trimmed is not critical. The techniques used matter more.
Most utilities require their line clearing arborists to adhere to generally accepted arboricultural standards, although the training and enforcement of those standards vary widely from utility to utility and contractor to contractor, and in fairness to them, if there is a conflict between electrical safety and reliability and the well-being of the tree, safety and reliability wins out. These contractors typically are paid by the mile (or other productivity standard) as well, so they have to work quickly, and sometimes don't do the best job.
In any case, utility easements give them wide berth to pretty much do whatever they feel is needed to ensure safety and reliability of power, so there's not a lot of recourse for the property owner. If you feel the utility trimmers did a poor job on your property, I don't know what state you're in, but in some states, the town tree warden has enforcement authority over any tree work done in the town. You can also complain to the utility.