In the second edition of Elementary Analysis by Ross in the proof for the theorem that states all bounded monotone sequences converge they have the following statement in their proof.
$U - \epsilon < s_n \leq U \implies |s_n - U| < \epsilon$
This is more of a clarification on the inequality. Wouldn't we need the inequality to be $U - \epsilon < sn < U + \epsilon$ to make the conclusion that $|s_n - U| < \epsilon$?