Hi John. To reiterate what everyone else has been telling you here, you're doing just fine. Don't let the naysayers get you down.
I made Master here back in April of this year, play everyday, am L88, and still have quite a many good rounds to go before I make Tour Master. Much of my delay can be attributed to the fact that a large percentage of the rounds I play are AS and don't help me in lowering my avg. And, I'm perfectly happy with that. I simply prefer that play format versus stroke play by myself or with others.
As far as avg vs tier goes, its pretty simple. Me, for example: I finally got to Master tier after getting avg below 67. Very next round after making Master I shot a 40 over 9 holes. This sent my newly reset avg to 80. Its taken me 6 months to get it back to where I started. Granted, I've been very slow at getting there for the reasons outlined above.
Bottom line is you're doing just fine and I don't see any reason anyone should be getting on you. You'll likely be hitting Tour Master any day now if you just keep plugging away as has been suggested to you here.
Good Luck, Have Fun, Hit Em Straight
Lashe