I think they just do whatever makes them comfortable sometimes. I caught one of my girls bowl-wrapping last night and she's in the same boat yours is in. Laid a clutch earlier this year and has not been paired yet. I also have a male who will occasionally lay inverted or on his side for seemingly no other reason than to get comfy. He's done it ever since he got over 1000 grams and there doesn't appear to be anything wrong with him.