This can be caused by many reasons, for example:
- the plant was replaced
- the plant is weak
- the plant lacks light
- it's too warm
- it's too wet /not too humid/
and some more

Milin

temperature shock(in warm store out to briefly cold parking lot to load up and drive home ect..)
do not move the plants once the buds form, you can move once buds begin to bloom that ok.