Thank you for the question.
I think what you are referring to is otherwise known as implant displacement where a breast implant can “shift” out of its ideal position. Examples of breast implant displacement include bottoming out, superior displacement, lateral displacement, and medial displacement ( symmastia).
Signs that a breast implant has shifted would include visual or palpable changes of the breast implant positioning, breast asymmetry, and occasionally discomfort associated with the implant displacement. Often, the nipple/areola complex can appear off-center on the breast mound if a breast implant displaces.
Your plastic surgeon will be a good resource to help you determine whether a breast implant has displaced from its ideal position.
I hope this helps.