Not just in the quote referenced above, but in Chapter 18 as well...

"I never saw you wear a ring before, Edward," she cried. "Is that Fanny's hair? I remember her promising to give you some. But I should have thought her hair had been darker."

Marianne spoke inconsiderately what she really felt -- but when she saw how much she had pained Edward, her own vexation at her want of thought could not be surpassed by his. He coloured very deeply, and giving a momentary glance at Elinor, replied, "Yes; it is my sister's hair. The setting always casts a different shade on it, you know."

Elinor had met his eye, and looked conscious likewise. That the hair was her own, she instantaneously felt as well satisfied as Marianne; the only difference in their conclusions was, that what Marianne considered as a free gift from her sister, Elinor was conscious must have been procured by some theft or contrivance unknown to herself. She was not in a humour, however, to regard it as an affront, and affecting to take no notice of what passed, by instantly talking of something else, she internally resolved henceforward to catch every opportunity of eyeing the hair, and satisfying herself, beyond all doubt, that it was exactly the shade of her own.

As if Elinor would not have noticed Edward surreptitiously taking a lock of her hair!

Elinor has been exhibiting shades of Mrs. Dashwood and Marianne whenever she thinks about Edward's unusual behavior!