This would be an incredibly inefficient way to transmit an STD, and the STD probably wouldn't have had time to infect her mouth to transmit.
However, if she gives unprotected oral sex on a regular basis, she could have an existing oral STD and transmit it to you. It's a lower risk than unprotected vaginal, but still a risk.
You could get gonorrhea, chlamydia, syphilis, genital herpes type 1 (if you don't have oral hsv1 already), and NGU. Most experts don't think one act of unprotected sex warrants testing. If you have a regular partner, it might be worth testing.