This really falls under OCD and limited knowledge of HIV / AIDS, you will find it that incidental exposure rarely result in transmission-and by rare i mean almost never. Especially in the scenario mentioned, so feel at ease and try to learn the real routes & means of transmission in regards to HIV / AIDS. The virus does not lurk on door knobs and gates, ect, we all have it, this is why you never hear about people contracting like this.
Non related to HIV transmission. Seek medical care for cat scratches.. that's all.