missing feathers

Hello, I am new to this forum, but I was brought here due to being concerned about my new lovebirb. He is behaving fine, eating fine, etc. however, I noticed his face was either missing some feathers or it looks wet or something? I got him around a week ago, I believe the petstore person said...

Hi, all. Yoda tends to pick at a small area where his left wing meets his body, up by his "neck/shoulder." It appears that the spot is missing some feathers, and he keeps pecking at it when he's active (or hyperactive). The bird-store owner didn't notice anything when I mentioned it to her, but...