Fighters scrambling at bases not under attack

[Mike_B20]

In a previous post I reported a high unexplainable sortie count.
A pattern seems to be emerging.

If there is a bomber attack on a base equipped with radar and fighters scramble to defend, often the next turn reveals virtually all other squads at other bases on CAP missions have scrambled as well, even though nothing has happened at these bases.

In a turn just played in a PBEM, my opponent attacked some transports at Wunpunko with Betties and Nells. This was the only air engagement of the turn.
My fighters at that base scrambled to intercept.
Next turn revealed all other fighters at other bases that had been on CAP at high fatigue levels.
Interestingly, two of my CV's fighter squads seem to have scrambled also, the other two CV's fighters had normal fatigue levels.
All CV fighter squads were on 10% CAP.