Ds2 Y9 self isolating for the 3rd time. Is this unusual ?

[Schonerlebnis]

Ds finished 2nd episode of self isolation on tues, back at school wednesday.
Thurday evening we received a text telling him to self isolate again....after 2 days at school I'm tempted to contact school on monday to make sure they were aware he was previously self isolating...hoping that it's a mistake and he's been included because he was on the class register for that subject. Anyone else have a child who's in and out like this ?

My Y10 hasn't had to self-isolate yet but that seems to be down to luck more than anything.

The school has had cases in all year groups (including Y10) but DD hasn't been a close contact of anyone testing positive.