Hi,
Let me say it again:
This is a Yahoo server side issue. It needs to be fixed there (except nobody at Yahoo seems to give a damn about it, since 2007).
It's intermittent, as in, can come and go as it pleases.
I've seen it in stock Email on a Galaxy Nexus with 4.2.2.
Don't know if Samsung's built-in email reports these errors at all, or if they prefer to keep you in the dark about login failures (K-9 works this way: no login - no mail - no error notification - no indication if the app is checking your mail or not...).
The issue usually corrects itself on the next mail check, so you can just ignore the error notification or turn it off in the app's settings.