Toto Drake - Loose Tank

Several years ago I installed 2 Toto Drake toilets in my house. They have been virtually trouble free, but I have noticed that on one of them the tank seems a bit loose. It will rock backward with a fairly light push. On the other toilet, the tank feels firmly attached if you gently push it. I did check the 2 bolts that hold the tank to the bowl and tightened them a bit (but didn't want to overtighten and risk cracking the porcelain). It's still loose.

I have 2 questions:

1. Since it doesn't leak, should I just leave well enough alone (or is this a problem I need to address now)?
2. If I need to do something, what should I do?

As long as you tighten each side a little at a time, and keep them even, you can tighten it up until it is nearly tight to the bowl. Actually you can have it tight to the bowl, but there is a fine line between just touching and bending then cracking it! Try putting a piece of paper under the contact point and adjust it until you can still pull it out. As long as you do this evenly and don't get compression contact (the porcelain won't bend!), you won't break a good tank. Or, leave it as it is...

Thanks, I took another look at the one that doesn't rock and can see where the problem lies. The loose tank is snug up against the bowl in front, but it leans forward a bit. As a result it is not making contact with the base in the back and will rock backward if nudged. Maybe I didn't install the gasket between the tank and bowl properly? Anything else that would make the tank tip forward a bit?