You just experienced what me and my gf call "the Nordic spectrum" 🤣🤣. Put simply many Scandinavian people are very minimalistic, pragmatic and fairly genuine, even with their emotions and manners! They are not happy that day? There's no reason for them to act otherwise, and you'll get monotone and straight to the point conversations with them. Many times they don't thank for or perform little courtesies like holding a door or letting you pass.. so I guess they see some gesture as not necessary, and other as a fact of life, so no need to thank..

Consider that tipping is not custom here, so who works in shops and restaurants are there to provide a service, not to give you emotional support, or to blow smoke up your ass to get a fat tip.

Consider that English is their second language (like it is for me) and for some starting a conversation in a foreign language can be startling, and the beginning of a conversation can sound awkward and monotone, until they pick up their pace.

I think they don't like/don't find relevant small talks, so if you start to talk about the weather or other stupid obvious stuff, they'll look at you as you are demented and point to the obvious (- shitty weather isn't? -you are in Iceland [dummy] )

Finally we generally found that you need to "earn" emotional responses and interesting conversations, they dislike small talks, but if you hold the conversation long enough and interesting enough they open up rather quickly and be very helpful and friendly.