Distance to the Moon is about 390 Megameters, time to orbit is 27.32 days, so speed in m/s is:

D*2*pi/T/86400 ~ 1040 m/s

Diameter is about 3500 m, so time of occlusion is:

3500/1040 ~ 3.36

More accurately, diameter ~ 3475m, hence

3475/1040 ~ 3.34.

Seems low to me.