58 feet of 16 gauge is a little long, but within generally recommended limits.
Crutchfield suggestions
You're aided by the big subwoofer that handles the bass, even for the surrounds. Bass consumes most of the power, so your surrounds (if set to "small") don't require that much.
If you were doing it over maybe 14 gauge would be a little better just for self confidence. But I think you're probably OK as is.
I recently switched my mains from 12 feet of 16 gauge to 12 gauge and I can't tell any difference. For my surrounds I use about 30 feet of Radio Shack 14 gauge flat under carpet speaker wire.
