Greetings, I just had a glass block wall built using glass mortar. It's completely dry, and I just noticed 2 small holes that should be filled. They are about 1/8" so very tiny. Should I mix up a bit of the leftover mortar and fill it in, or should I buy some type of caulk? Also, since it's a shower wall, can anyone recommend a waterproof sealant? Thanks!