No, it's not a sign of imminent failure. The "faucet" is called a "hose bibb" and has a small gasket inside it just like the outside hose bibb that you connect the garden hose to. These gaskets rarely are used, on the water heater, and that it is showing a small leak, probably implies that someone turned it open for some reason, and didn't get it adequately closed. Many times these are plastic hose bibbs, and can be broken, so carefully try to tighten it closed so it stops leaking, and enjoy the seventeen years it has offered you flawless service.
: There is a small amount of water coming out of the "faucet" in the side of my water heater. The place where you would screw in a garden hose if you wanted to drain the water heater. It's 17 years old, and I wonder if this is a sign of imminent failure.