In my experience, an increase in lying down(stretched out) generally means one of 3 things - pregnancy, heat stress or tummy problems(i.e. gas bubbles, which indicate GI problems). Since pregnancy isn't a factor here, cool down the room Sammy's in, and be hip to increases in temp. I'd also start giving infant simethicone right away - it's a benign med, and could ward off the stasis issue. Also cut out raisins and increase hay consumption.
Chins often do sleep in stretched out positions, and that's normal for them. But when you notice a change in the frequency, or the stretching out position seems very exaggerated, you need to check it out. Without sounding paranoid, any change in chinnie behavior is a signal that something's up, and it's important to be proactive