It can be. When a foundation settles unevenly, it racks the door and window frames out of square, so they bind or show a triangular gap at one corner. Seasonal humidity also swells doors, so timing matters. If sticking comes with cracks or sloping floors, get it evaluated.
More detail
Sticking doors and windows are one of the most common early symptoms of foundation movement, but they are not always structural, so the trick is reading the whole picture. When a foundation settles unevenly, it distorts the framing above it, and rectangular door and window openings rack into parallelograms. The classic tell is a door that binds at the top on the latch side while a triangular gap opens at the opposite top corner, or a window that suddenly will not slide. Crucially, this kind of sticking is usually directional and persistent, and it tends to appear alongside other signs: a diagonal crack running from the upper corner of that same door or window, gaps opening between the wall and the ceiling or floor, or floors that slope toward the affected wall. The benign explanation is seasonal: wood doors and windows swell in Cincinnati's humid summers and shrink in dry winters, so a door that sticks every July and frees up every January is probably just humidity, not your foundation. The way to distinguish them is to look for the accompanying structural signs and to track timing. If the sticking is new, getting worse, concentrated at one corner of the house, and paired with cracks or sloping floors, that pattern points to settlement and is worth a free inspection where we measure floor elevations with a manometer or laser level. If it comes and goes with the seasons and there are no cracks, it is likely cosmetic. We will tell you honestly which one we think you have rather than selling a repair you do not need.