It's certainly normal for a woman to be so focussed on labour that she becomes unresponsive, but not that she stops breathing.

Is it possible that DH was very worried and interpreted your focus on labour and how much of your attention it was taking as a crisis (since he asked for an epidural on your behalf - seems very strange to me!)? So many men just don't know what to expect and the way labour looks can be so far from how it feels.

When i was at the end of labour (2nd stage but roaring rather than pushing) i know i was so relaxed between contractions i was drolling onto the pillow i was leaning on. XP wiped it away and laughed at how zonked i seemed and i can remember mustering a smile for him then because i FELT out of it.

Did a midwife comment on your breathing? I'm not too sure what effect peth would have on you in that way.

Bx