HAGERSTOWN, Md. — He said he still gets “amped up” before he steps to the mound in the first inning. After those initial warmup pitches, the adrenaline rush of being back in the comfortable place that was taken from him nearly a year ago can still be overwhelming for Stephen Strasburg as he continues to work his way back to Nationals Park. Strasburg’s nerves were palpable as he made his fourth rehabilitation start on Monday, for the Class A Hagerstown Suns.