What’s wrong with this sentence from William Boyd’s ORDINARY THUNDERSTORMS?

From Ordinary Thunderstorms by William Boyd (NY: Harper Collins Perennial, 2010), p. 191:

He shouldn’t have thought of Alex, he realised, as image after image came swimming uninvited into his mind, and he could hear her husky, throaty voice in his ear. In fact it had been her voice that attracted him initially — as if she were recovering from laryngitis — and was the first thing about her he had become aware of [...]. [...] The physical presence of Alexa — the thick blonde hair, the tan, the briskness, the teeth, the glossy lips — almost contradicted what her vocal chords seemed to infer.  It was as if he had been expecting some stout, heavy-smoking lounge-singer and instead had been presented with this glowing prototype of American pulchritude.

Can’t spot the error? Email editor@readswell.co.uk for an explanation.