Shivering is a common side-effect of general anaesthetic. I've not seen enough post-op recovery to know exactly how common, but it's high on the list of side-effects we have to tell people.
WRT the hypothermia, you may have been slightly hypothermic as a result of having so much of your body surface exposed to the air. People don't realise that ambient temperature (18-22C) is actually quite cold in relation to body temperature (36.7C) - it's only the fact that we wear clothes that means we don't feel it.
Nowadays we have heated blankets in theatre too, to offset this heat loss.
WRT the hypothermia, you may have been slightly hypothermic as a result of having so much of your body surface exposed to the air. People don't realise that ambient temperature (18-22C) is actually quite cold in relation to body temperature (36.7C) - it's only the fact that we wear clothes that means we don't feel it.
Nowadays we have heated blankets in theatre too, to offset this heat loss.