Working with dough

This is an intriguing question, and it may have something to do with overall kitchen temperatures (as Batman linked to in comments). Temperatures can have a significant impact on how sticky or pliable dough is, especially if it contains temperature-sensitive ingredients like butter. If spring days tend to be a little cooler in your house, but fall days are a little warmer, that could be one possible source for a difference. (Even if your house is climate controlled all seasons, people tend to keep homes a bit cooler in the spring since they're used to the cold winter, and they tend to leave homes a bit warmer in the fall, since they're used to the summer weather.)

However -- assuming your kitchen temperatures are roughly the same during the seasons you mention, my guess is that this is a humidity issue. And not just the ambient humidity in your kitchen. Flour tends to absorb some ambient moisture during humid seasons and "dry out" more in less humid seasons. It's not a huge effect, but it can be big enough to make a difference in dough handling.

If your flour has been exposed to such seasonal fluctuations in processing or storage (before and/or after you purchased it), it may vary in moisture content. The flour that sits in its paper bag package in your cabinet during summer months might have gained 5% in weight or more, just from the added moisture. In winter the opposite can happen (and with bigger humidity swings, flour weight can vary by 10% or more).

If you add the same amount of water (or other liquid) to the same volume or weight of "humid flour" vs. "dry flour," the "humid flour" dough will likely be more pliable or stickier. Most bakers traditionally make small adjustments to any final dough by adding a little liquid or flour.

One final note: flour used to vary a lot more seasonally in strength (i.e., gluten content, which will effect how stiff or pliable dough is), as various wheat varieties were grown in different seasons. That still takes place, but most manufacturers try to produce a constant blend of "all-purpose" flour that has roughly the same characteristics year-round. If you live in an area of the world or source your flour from somewhere that doesn't try to maintain that consistency, it's also possible that your flour is somewhat different when you buy it in different seasons.