Hey Dido,
Nasty experience but yes it does happen. It's possible to do all manner of things while hypoglycaemic, including eat, talk, drive, which subsequently you have no recollection of doing. I've certainly been there, and to this day cannot recall stuff I was doing AT ALL in the build-up to going really low. Fitting is not good, you can do yourself real damage during such events, again this has happened to me numerous times and I have the collateral damage and scars to show for it.
Having a bath might have contributed to the situation, some people report that bg levels can drop quite severely afterwards. I don't know about this as I rarely have a bath (and before you say "Eew" I shower!). It's also possible that your injection may have been delivered to a blood vessel instead of to fat, which does happen sometimes, meaning it's going to act a lot more quickly than you expect.
How is your control normally, and had you had any hypos - even minor ones - in the days before this happened? How long have you been diabetic, and how long have you been using NovoRapid? What is your hypo awareness like? Any complications? It might be worth running higher for a few days, if only to ensure your stores of glycogen are back to normal.
Top marks to your husband though, keep hold of that one!
All the best, Jo