Yep, sure is a possibility.
Easiest way to check that is putting a straight edge across the blades. Or clamp a straight edge across the deck and measure down to the blades, as long as the blades are all parallel you are good. Measure from one end of the blade to the edge, then from the other end of the blade to the edge, and clamp the edge so these measurements are the same. All the blades should measure the same to the edge from both ends of the blades with they are parallel.
Spin the blade 180 degrees And check they measure the same from either end. This will tell you if the blades are belt or if the deck is bent.
Check the spindles aren't bent by spinning them by hand while looking at the nut that hold the blade on. If it wobbles about you have a bent spindle.
A well aimed whack with a hammer will straighten your deck in short order once you determine where the deck is bent.