Moisture content of the air tends to change winter & summer - warm summer air is more moist than cold winter air. It may well be that the wood is naturally contracting & expanding due to its moisture content.
It may also be that the dresser is old and has been subject to wear over the years. If it were mine I would inspect, and expect to replace, the drawer runners. I would not mess with the drawers themselves.
Good luck...
Peccavi
January 2010
howtomendit.com for free repair help, information and advice.
