Well, it certainly says something if you guys talked bout no nudes. Sometimes I think guys get a little confused though, especially if you've been talking and flirting for a while. He would almost certainly welcome any kind of nudea from you because men tend to be very visual when it comes to sex, so maybe he thinks hes teasing you in a way? Like giving you a preview of the goods? Lol
When I was first talking to my now husband we were kind of sexting one night, not super sexual or graphic but using a lot of innuendos and being very flirty. Anyway, I forget how it came about but I said something about a pole or rod or some other term for a penis and he took that to mean that I MUST want a picture of his. I tried to not make him feel bad of embarrass him, and I actually thought it was kind of funny he thought I'd get so aroused by a picture of it. Long story short, maybe he didn't mean it in a throwing it in your face kind of way? I'm glad I didn't use that as a deal breaker, because god damn do I love that dick now ;) ha