This has happened to me as well. I would say it’s nothing to worry about, as a lot of factors can be at play such as diet, if you have eaten, underlying illness etc. I have been with guys that taste very strong while my current SO is very pleasant (as pleasant as it CAN be) I think due to his diet and water consumption.

In fact, I distinctly remember a time my first semester of college giving my boyfriend head, swallowing, then running across campus for an exam and feeling really nauseous. While that wasn’t the first time I had swallowed, it was still early on in my sexual history so there may be a correlation there. Anyway, I wouldn’t be concerned unless it truly does become an issue in the future, in which case both of you should speak to your doctors.