Dashed Bar-Lines Appeared In A saved Score

On opening a score saved yesterday, some bars appeared with dashed bar-lines. I didn’t put these in, they just appeared.

There are no time-signature changes, changes of clef or anything else I can think of that might cause these.

It’s not a problem as I just changed them back; I’m just curious.

Thanks.

Does your project use aggregate time signatures, e.g. 3/4|4/4 or similar? Those will automatically show a dashed barline at the dividing point between the first and second meter in the bar.