It's about time really. Too many seasons have had a moment where someone Dex knows has almost found out - most notably at the end of S5 when only a plastic sheet prevents Deb from finding both Dex and Lumin at the scene.
When you see Deb enter the church, there was a small part of me that thought that something would happen so she doesn't see Dex, like she was in the wrong part of the church or something. So when you see Dexter from her POV it was the massive payoff that we've really been waiting for. Personally, I thought this season was going to end with Deb kissing Dex.
Next season, I don't know. That's the main question, isn't it? Deb is in love with her "brother" but even she has to now figure out that Dex is the Bay Harbor Butcher, that Doakes was wrongly accused and every time he missed an appointment or acted strangely it's because of his "second life" as a serial killer. So, will we see Dex arrested and jailed? Seeing as it's been renewed for another 2 seasons, it's unlikely either of them will have Dex in prison. So I'm wondering if she'll cover for him...