I think we have to be more logical and practical while analysing the problem. Foremost, the virus stays outside the body alive for not more than 45 seconds. An infection through a pen tip cannot happen within 45 seconds after it pricked another person.
Health consultant have to be careful while using needles as the chances of getting pricked after being used on a person could be considerably high. However, the chances are lowered due to proper handling and disposable needles.
So, in your case, the chances are negative, and you need not worry to this extent. In day to day life, we even cut ourselves with knives and sharper objects while working. But we dont have to take these incidents to our brain and spoil our day.