A picture of the bugs would really help. Also your zone and area gives a better idea on what pests might be in your area. Are they eating the leaves? Do they have shells that drop and can be seen as little crusty bits around the leaves below infestation?

Was it a mealy bug?

I'll bet that he/she is seeing the cabbage aphid, which would be a perfect match with the given description.

Fastest method to be rid of them is to blast them away with fairly sharp sprays of plain water. The water should be strong enough to knock them off but not shred the kale to smithereens.

Sounds like cabbage aphids to me, too. I have done the water spray and it works reasonably well for me. Another option is to use a mix of soapy water and spray the bugs with that.