Well technically Cassie and Tim kissed more than once and were so obvious about that it was called out/teased on by WW and by the other Titans. Did Johns forget his own story or was Cassie rewriting what happened for Kon's benefit (along with being the High Priestess of the Cult of Superboy and all).
And I don't think DC will the pregnancy route with these two at least as long as they are underage and unmarried. Especially with WB providing more corporate oversight to DC and the "Super" and "Wonder" brand names. I do wonder if this long-distance relationship will work though, Johns (and I presume Levitz) seem to be giving Kon his own Smallville supporting cast (complete with Lana Lang and Lex Luthor analogs) away from the TT and Wonder Girl.