Any time you are unable to OLCI for any passenger, unless there is a clear explanation such as missing documents, you should immediately call the operating carrier.

Anecdotes do not help in these situations. While the issues are almost always insignificant, they sometimes are not and they sometimes require time. If insignificant, you have peace of mind. If not, it is far easier to have a problem resolved with the benefit of time, a comfortable chair and a speaker phone on mute while you wait, than the clock ticking at a counter.