one plugin need update three get updated

hi to everyone and sorry for my poor English
I have latest version of all plugins installed
yesterday i have noticed my wordpress seo plugin by yoast need update
i check the name of it in update box and start update
but when finished i notice wordpress say three plugin updated
first it was wordpress seo by yoast
second wast mailpoet
and third does not have any name
this problem occured today for second time when i only update wordpress seo and there is no notification for any other plugin
my mailpoet plugin and an unname plugin get updated
does this is a common problem or does my site hacked?
thanks for your answers