What would cause guitar strings to seem to tighten, in 48 hours?(Details.)

I tune my acoustic guitar, once every couple days.
Two days ago, I just tuned it.
So. All keys were adjusted correctly.
It is natural for the tune to need to be tightened after lots of playing. As stretching, can pull the strings out of tune.

Tonight. My guitar sounded weird, so I broke out the tuner.
To my surprise, every string needed to be loosened significantly.
This has NEVER happened to me, in the 30 years I’ve been playing.
I used the same tuner. “Guitartuna.” On an android.

I play lead, or accompanying, and really bend the strings, so they loosen quickly.

Any ideas?