A piece of advice:

Print out the information about the Free Movement Provisions, and take it with you.

I don't think it's very likely that you'll get problems with the Greek immigration officers (who are, after all, trained as immigration officers and who should know the rules). However, having the information in writing may come in useful if you come across an officious check-in agent who thinks he/she knows the rules but doesn't. I've come across a few of those over the years, including one who refused to let a Dutch national check in for a flight to the UK on the grounds that his passport only had five months to run!