Yep, it's a freshness issue. I once catered an event and the hostess asked for deviled eggs; I forgot to buy them ahead of time to let them un-freshen for awhile before boiling, and I went through three dozen eggs hoping to have gotten some that were old enough to peel well.. no dice. I had to refund money to the hostess, and I had lots of egg salad that week. :)

Have you tried shcoking in cold water after boiling? I never have this problem and in addition to boiling for 8 min I shock in cold water.

Fresher eggs will be harder to peel. In the food pickle search bar type "boil egg", and you will find a really good thread on the topic.