time difference between proceeding lines

diff.py

from datetime import datetime, timedelta
import sys

last_t = None
min_delta = timedelta(seconds=1)
#2016-02-05T09:46:33Z
for line in sys.stdin:
  t = datetime.strptime(line, "%Y-%m-%dT%H:%M:%SZ\n")
  if last_t:
    diff = t - last_t
    if diff > min_delta:
        print "%s - %s since last spike" % (t, diff)
  last_t = t