In more than 50 years of shooting woodies, I have had a few, a very few, get soft. Usually that was after 5 years or more and the finish was also compromised. Most of my target shooting woodies don't last that long. I break or lose them before that.
It's possible, but extremely rare. If the finish becomes compromised, the arrows can take on moisture, or shed it, with commensurate changes in straightness and even a little spine. Of course, how they re stored can also affect their straightness, as already noted.
I'd check them all for straightness, and straighten any that need it, and check the finish. It may need to be touched up as well, particularly the couple of inches right behind the point, where it usually wears off.