We learn from Egwene (I totally forget which book), but she says she has evidence that some of the sister following Rand were under compulsion. However, I cannot remember if Egwene is referring to the 51 bonded by Logain and his crew or if Egwene is referring to the Elaida followers who were held captive by the Aiel and who eventually swore to Rand (with a little help from Verin).

If I remember correctly, Egwene describes the compulsion as something to the effect of (paraphrasing): "We know the sisters at Cairhien were compulsed."

I always thought this meant that somebody had discovered Verin's compulsion, and that Egwene was mistakenly blaming Rand for it. I could be wrong though. My memory of those sections of the books is foggy.