Thanks for writing.
We do not see HIV passed through receiving oral sex. We would not recommend HIV testing if the oral sex you describe is your only risk for HIV. However, other STIs are easily passed through oral sex.
Other STIs that can be passed through oral sex are: Chlamydia, Gonorrhea, Syphilis, Herpes, and HPV. We would recommend STI testing for anyone who is sexually active.
You’re correct that the chance of getting an STI from 5 seconds of contact is low, but it’s not impossible.
Hope this helps. Please feel free to comment below or submit another question as needed.