Our 3 yr. old female has never been very social. She'll let you pet her, but only on HER terms, and never for very long. She doesn't like being handled and clipping her nails was always a 2 person job (ever since we got her at 8 weeks old). She very rarely purrs. But for the last 2 months or so, she's done a near 180 degree switch. She's friendly now. She'll cuddle with you at least once a day, she PURRS!!! and she will let you do her nails while she dozes (she'll twitch her foot every once in a while, but doesn't take off at a dead run like she used to) IT'S WONDERFUL!! I was sitting crouched on the floor a few nights ago, and she waltzes right up to me and curls up in my lap. Although her definition of "curl up" is jump up on your lap, select orientation and softness of thigh, then flop, and just hope you have a free hand to keep her from sliding right off! Then she's bury her nose in your armpit, make a deep sigh and off she goes to la-la land.
Meanwhile, both your arms are occupied with holding on to her. We're holding our breath that this change is a permanent one!!!