Most likely a low dosage/concentration of it and only touched not ingested.How come it's so slow acting? according to many articles Novichok is 6-8 times more deadly than VX nerve agent and 1 drop can kill up to 10 people (more if inhaled) but in both cases the victims were exposed at an earlier time and place.
Concentration is a very important yet often overlooked factor with chemicals, I.E a glass of pure Fluoride or Trisodium Phosphate will kill you, but in small amounts they're harmless hence being used as additives in tap water and cereals respectively.