New Behavior as of Tonight

I've had this 7 month old girl for 2 weeks now. Bloodwork was clear and she got her shots. She also got a leg amputated because it was broken. Tonight she started doing this thing where she'll flatten on the ground and trill. Sometimes she rolls (or writhes) while she's at it. Once she did it while calling out but not looking for anyone in the house. Appetite, thirst, and potty breaks are all normal, but I'm a bit concerned since the one where she was calling out and crawling slowly. Does anyone else's cat do something similar?