It appears as though the door or frame has shifted and the deadbolt no
longer lines up with the catch in the door frame. Normally I'd attribute
this to settling or shifting, but the gap around the door is still
consistant and I can't find any evidence that anything is out of kilter.
The
deadbolt appears to be as much as 1/8' out of line with the catch in the
frame. The door latch still engages and I can lock the door using the
knob,
but what shifted to put the deadbolt out of place?


Don't know where you are. Don't know how the garage is constructed.
Don't know if it has footings.
But here in the NE US, right about now, it could be due to frost heave.
One side heaved more than the other?

24'x32' on a 6" slab (no footings) in Calgary, AB, Canada... Just finished
a bout of -40 degree weather. 2"x6" stud wall construction.

I'd agree with the heaving, but I can't find any evidence of movement. I
just thought it was very odd.

Going to investigate further this weekend...