Well, don't worry too much yet. It could just be baby regurgitation from a full crop as others mentioned. Somehow I missed that this was a bird still on formula. The Meyers was weaned, but also just awfully young to be showing those behaviors already. I was very, very surprised when my sister began asking for advice and I heard what he was doing. But, if her bird could do it as a baby, I figure others might also.
I'd be careful where I pet him (or her). I'd mostly pet the head and not the belly, back or tail. With boys you don't want to pet their belly and with girls you don't want to pet their backs. Since you don't know yet, avoid both.
My conures are/were both female and had no interest in mate bonding with me. Rowdy definitely knows the difference between men and women. She does flirt with most men she meets (or sees for a few seconds), so I don't have a lot of experience with this kind of thing. I think the amazon is a male but he's never actually been DNA sexed yet. This is my first time being openly courted by a bird. As I said, if he gets started, I just put him back in the cage or on his play gym and ignore him. I don't get upset or yell at him or anything like that. If he's in his cage already and making his moves, I just ignore those as well. I do praise him for other friendly and funny behaviors like hanging upside down and flapping his wings for me, or stretching.
If it helps, my understanding is that conures are not as bad about these things as some other species

I am just trying to ensure my amazon doesn't turn out like my sister's Meyers did. He got to the point where he was attacking her left and right. Her husband was not at all understanding and snapped the bird in his beak, which made him unable to be handled by anyone. I didn't have the time to devote to him and finally talked her into giving him to a good rescue that had people who could work with him. My understanding is that he is back to being a good pet and has been adopted. I would have taken him had I not been working 2 jobs then and had many other pets who needed my attention.