The kits were sold in five provinces and traced back to Salinas, Calif.
They suspect another E. coli outbreak.
A string of illnesses was linked to E. coli in the lettuce in October.
The agency has stopped short of issuing a recall.
The bacteria is behind a recent string of illnesses tied to romaine lettuce.
Fifteen people in Quebec and three in Ontario have fallen ill.
The CFIA says if the contaminated lettuce has entered the Canadian market, it will issue a recall.
There have been no reports on the onset of illness since Dec. 12.
The grocery chain says it's a precautionary measure.
An E. coli outbreak has been linked to one death and 40 illnesses.