First, we start this upswing with less spare capacity than some previous ones. After a big recession, it usually takes some years for well-above-trend growth in demand to use up the spare capacity created by the recession. This time that process will not take as long.
Most measures of capacity utilisation, unemployment and underemployment are much more like what we saw after the slowdown in 2001, than what we saw after the recession in the early 1990s. This is not a problem. In fact, it is good. It is a goal of macroeconomic policy to try to keep the economy not too far from full employment.