Information:German citizen with an electronic european passport; don't usually need a visa to enter Canada, just a work permit to work, or a study permit to study.
Entry shouldn't be a problem, BUT!!! it depends on the case.
Request your CAIPS from here
http://www.caips.ca/ after 30 days, you'll find out if they have any particular remarks on your file, + I would also advice you to go to the nearest IMMIGRATION OFFICE IN CANADA, or to write to them, Ask them for permission to leave, or let them know you are traveling for visiting Grand parents, & that it's urgent.
A Visa doesn't grantee entry in Canada. it's all about how would you handle yourself at the point of Entry with the officier, & what's on your CAIPS file. that's all.
Being paranoid is a good thing with CIC, you never know,
Also if you can afford it, take your spouse/common law parnter with you, so it looks even better that she met your family, & it would be much easier to come back if she accompanies you.
GOOD LUCK.