I've been very diligently re-engaged in practice for three months now. It's going well, I feel like I can open up pretty fully and quickly. And my kundalni has reawakened (it had actually gone dormant while I had been diligently practicing before, so I'm in that sense ahead of where I was).
But I was experiencing what I called "slipperiness" before. My prana didn't stick anywhere, I could move it or let it move effortlessly. Spinal breathing wasn't like sucking up thick fluid through a thin straw, it was more like turning on a light saber. And only now, after 3 months of practice coming after a two week lapse, am I beginning to feel that slipperiness again. We don't understand how blocked we are until we become unblocked (in fact, we don't recognize the blocks as blocks, they seem "normal"). But after lapsing practice and regaining those blocks, I still wasn't fully aware of the blocks until the second unblocking. This, from my posting above, is, I think, a real good explanation:
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we're all so accustomed to living a life of grasping and anxiety that we can revert quite far to that before we notice how far we've devolved. I'm starting to get back to The Flow again, and I can see quite clearly how much mud had splattered all over my windshield (a lot!!). It didn't feel that dramatic at the time. The cleaning (via AYP, etc) feels dramatic. The backtracking feels normal. Beware of this, because it's like quicksand.
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I should note that none of this is scientific. Perhaps after my lapse, the mantra was working on different parts of me than before, so certain things cleared out before the intervening stuff was cleared. Who knows....you could go nuts trying to figure it all out. But this is for sure: lapsing practice is a baaad idea.