Excessive belly fur shedding

[AngelaH]

In just the last few days I've noticed lots of belly fur left behind after Thistle has been laying in one spot (for example on my shirt). There's always been the occasional few, but is will be like 20-30 little hairs left behind when she moves. Any one else experience this ever? Thoughts?
Some more info:
Age: 1 year, 1 month (been with me almost a year)
Weight: 314 g
Food: Purina One Beyond, no change in eating habits, but very picky eater
Activity: moderate runner at night, cuddler when out of cage (no changes)
-No quill loss or excessive scratching
-Skin is occasionally a little dry, but nothing serious and no changes
-No changes w environment (such as different fleece, detergent, cleaners etc)
Basically, I can't figure out why she's suddenly losing so much fur when nothing else is any different at all.

[AlexONeil]

Houdini went through a phase at the beginning of winter when he was dropping hair like crazy. I never found out what it was, but it only lasted for a week or two.