She probably has an infection in her tear ducts - or some kind of infection. Aiko had lots of goop like you described when I took her in for it.
It will clear up with some ointment. Don't worry! But definitely take care of it right away - as if left as is, can cause all sorts of problems, including blindness! (This is what my vet told me, not my opinion.)
Hope your pup get better soon