interim EAD experience

On the 91stday of EAD renewal from vermont, a week before the old one expired
Jan.14: applied for interim EAD in Baltimore office
Feb.17: EAD interview, got it only after about 10 minute's processing. Note;there is a 16 day's gap from the expire date of the old one to the valid date of the new one. Actually stayed home already for a month.
Feb.18: green card interview, stamped. BCIS asked for the new EAD back.
Only one day exactly used on the interim EAD! Even I didn't keep a copy for it!