At least two things here. First, there has been an increase overall in bicycle commuting over the last several years. The increase has been very slight, but measurable to those in charge of measuring. Second, there is always a "fair weather" increase this time of year. The days are long and the weather is nice so people are encouraged to get outdoors and get a little exercise. When the weather turns this fall and the days start getting shorter, you'll have your chance to decide whether your bicycle commuting was part of the overall increase, or simply a "fair weather" up-tick. Either way, enjoy the ride.
-Kedosto