Then touch very lightly and go, or touch very lightly, pause while keeping virtually no weight on the bars, and go. There is no reason to put weight on the spotting bars (or the chest for that matter.)
The bars should not be unequal height. If they're equal height yet you don't touch evenly, the problem is form. And if you only touch lightly, as you should, it should not throw off your balance.
There is no reason to be resting significant weight on the spotting bar at the bottom of the rep: both hands should still each be carrying almost entirely half the weight of the bar.
Anyway, you either have a non-problem or at the worst, you say it's a fraction of an inch so it should not be hard finding something thin, like a very thin piece of plywood or an exercise mat or something, to put under your bench if you instead want it exact. As others have already mentioned.