Multiple Stalls for one Pork Butt?

I'm smoking a butt <insert joke here>,...it's only my third, and things are going along nicely, but I've notice something on this one I haven't noticed before on the other two. Did I just miss it, or is this odd?

It is (was, anyway, before I trimmed it) a 7 lb Boston Butt. I started it at 1930 yesterday, and when I went to bed, it had stalled just under 160. When I woke up it was in the 180s, and stayed there a bit. Not too long ago, it was at 197, but now the temp has dropped to 193, despite the pit being steady (even getting a little hotter).

Is this normal and I just didn't notice before?

Thanks ahead!
Andy

EDIT...that "mini stall" or whatever it was lasted an hour or so....temp went from 197 down to 192 and stuck for a while. All the time, the smpker was at 275+/-. It finally ended and climbed quickly to the 200 I was shooting for. It's resting now, and smells great! It partially fell apart taking it off the smoker, so it may be a bit over done? I guess I'll soon find out.

The fat is melting and your probe could be setting in a fat pocket. I always take the butts I cook up to 210 degrees or higher. I have several stalls and seems normal. One other thing leave the lid closed, a lot of heat is lost and prolongs cooking time.Remember this is my ideas and experiences, always open to better thinking processes!

When that happens to me I start probing for tenderness every 15 to 30 minutes. Were you wrapping? Sometimes a pocket forms in the foil and that allows more evaportive cooling and causes a 2nd stall.