Jack Russell licking Greyhounds eye. Affection or indication of a problem?

[GruesomeShellChillingTortoise]

Just recently our 18mth old Jack Russell has started licking my 7yr old Greyhounds eye. He will lick at it for ages if i don't stop him. Greyhound seems content to let him do it.
I can't see anything wrong with either eye but could this be a sign of a problem/infection or just affection?

BUMP

generally affection many dogs just love to lick their friends. If you are unsure though I would pop to the vet for a check or look carefully at the eye but it is comman behaviour to lick other dogs especially eyes and ears