Social security number! Is it stolen? Help!?

I was online applying for a work permit. I am 16 years old. While applying online for my permit, I was scanning my computer with my virus protection. The work permit application asked for the last 4 digits of my social security number so i entered it in. Then I submitted my application in. My virus protection just finished scanning the computer. It detected this virus called Mal/Behav-285. I know that viruses steal information you enter in. Will it be able to steal my social security number even though i only put the last 4 digits in? By the way I entered my social security number before my computer detected this virus.