I can't imagine enough sperm getting to your vagina in this manner. A good glob of semen would be necessary before you start to worry. Do you know about the fertile window? Google that to find out more, and download a period tracking app so you understand better your high risk days.
You are not at risk from this particular situation. It seems likely that you are starting to engage in sex. It would probably be a great idea to keep protection around so it is there if you need it! Take care.