Interestingly, other communities seem to have had more experience dealing with this directly; creepers are not exclusive to the contra dance community, but perhaps in this case we can work with other communities to be less naive.
(I also find the creeper link interesting because contra culture has folks looking into your eyes frequently, which is described as possible creeper behavior in the swing community...but this, too, ought to be negotiable if it makes your partner feel uncomfortable...look at their ear, or their forehead....)