Is a gift expected?

When my two grandchildren graduated high school four years ago I gave them each $5K to use toward university expenses. They have both just received their BAs and are planning on continuing their educations. My question is: Do you think that they or their parents are expecting me to give another gift? Is a gift usual at this juncture? And if so, what is suitable?
Neither me nor my own children reached this point in our education and I have no experience here.