Cries before nap

Tisha is an 18 year old Persian/American short hair mix. At her age she sleeps a lot. When she is standing on her blanket, before the circle-plop maneuver, she cries out once or twice. The cries are plaintive sounding and projecting. They're much like a cat in heat only not that low-pitched and guttural and are shorter in length. I'm guessing it may be due to arthritis. Any ideas. Thanks.
Jim

Congratulations on having an 18 year old cat! As for the crying I would take her to the vet for a complete physical - bloodwork, fecal, urinalysis, etc. If the problem is arthritis the vet may prescribe anti-inflamatories. I'm sending good vibes for Tisha to get better.