He was not old, no. But 2008 was the year he started visibly struggling with his form throughout the season, which was in start contrast to the 4 previous years. If you want to argue his form didn't drop and he started losing to players he routinely beat in the past because of his main rivals, be my guest.
In 2009 Federer lost the AO final to Nadal in an tough 5-setter, I don't see it as damning loss because Nadal playes one of his best AO matches.
2010 again some unusual Slam results across the board. Again, the drop in form that had little to do with playing Djokodal.
2011 was a very good prime year. That's where the amazing rival competition came in to spoil the results. Still Federer did stop Djokovic who entered the Punisher mode and then was a point away from stopping him two times. Quite a feat as a Rafa fan would know.
2012 was a very solid year, more positives from that than negatives. Really not much to explain because Federer had great results, clear second only to Djokovic who he beat for the Wimbledon title. The loss to Nadal at the AO was not egrigious at all. Roger was playing well enough, Nadal was simply better. It happens to the best of them.
2013 doesn't need any comments.
I'm glad for you, now that you get to boast you fave's Slam record. It is a great feeling. But think twice before you decide to be a hypocrite and make BS claims about Federer, because on this forum there are plenty of posters to call you out, and that's probably not a great feeling.