Recently, I placed a bet on sports match, and somehow, I was very certain I was going to win it, the match started and at the end, I won my bet, odd was 1.4, not going to mention the amount I used for bet, but I won a good sum, i wasn't all that excited because
Then I remembered that some time ago, I was playing plinko with a random balance that was remaining on my account, I wasn't expecting any winnings, I just wanted to have fun and empty my balance, I set the risk level to "high" and was betting $0.1 on each ball that came down, I can't tell how many rounds I've played but soon enough, my account balance that was below $5 was already $40+, this money was not near the amount i won from sports betting but I was overly excited
Though, it's true that when we win a bet we least expected, we are likely to be very excited, but normally what excite gamblers the most is not if the winning was expected or not, but the number of odds been won that usually determine how happy a gambler will be at the moment, which is not different from your story given above.
However, looking at this case from my own personal point of view, it's obvious the reason why you weren't happy in the first instance was simply because the odds won was just mere 1.4x of the wagered amount, that is, if the betting amount was $10, then it just means amount won was $14 (i.e $4 profit), unlike in the second instance where you were able to win $40+ with just mere $.0.1, which was approximately 400x, a reasonable amount capable of making someone expected.
So in conclusion, I'm still stand to say that the mood was not what excited you, but it was the winning odds that did.