Object style overrides

(FM12 on Win7x64)

Anyone else noticing unexpected overrides on object styles?

Object styles "govern" each text frame on my master pages.

After content editing on Body pages for several days, I returned to the master pages and noticed overrides on every text frame that has an object style applied.

Any ideas?

Related question: how do I clear an object style from an object, so the object properties do not change and the style is not applied to the object?

Best regards,