Differences between matlab's 'impulse' and 'lsim' command; create impulse response
Indeed the lsim function is returning scaled values. You might also notice that it is connected to the gain $k$ of your filter:

[z,p,k] = tf2zpk(sysD.num{1}, sysD.den{1});


That will return:

k=0.002

You can scale it back by the sampling period as you noticed.