For what it's worth, I had a student that I solo'ed at 65 hours. I was his fourth instructor and I guess I was picked as a "last resort" before him being kicked out of the 141 program. The up-side is that he solo'ed, and is sort of on his way to doing something that he really wants to..., the down-side is that I doubt if he will have the ability to finish the private pilot course, and if that occurs he will certainly wash out when he gets to instruments...not to mention the fact that he's spent a TON of money and should be working on his instrument rating by now, instead of still trying to figure out how to flight plan...*sigh*
My point being, go ahead and compare yourself to others to see how you stand, and don't sweat the small stuff like a 10-15 hour difference between when you solo'ed. The important thing is that you DID solo (congrats, by the way), and you're on your way to that cert!