Open-mouth kissing is considered a very low-risk activity for the transmission of HIV. However, prolonged open-mouth kissing could damage the mouth or lips
and allow HIV to pass from an infected person to a partner and then enter the body through cuts or sores in the mouth. Because of this possible risk, the CDC recommends against open-mouth kissing with an infected partner.
One case suggests that a woman became infected with HIV from her sex partner through exposure to contaminated blood during open-mouth kissing.
So to answer your question you have little to worry about.