The call involved two engineers, we firstly spoke about ourselves, background, interests etc. and a few behavioural questions.

We then jumped into a coding exercise which is not on leetcode, I would say it was of medium difficulty.
The solution came to me instantly and I explained what we had to do and why. I coded a semi-working solution in around 10 minutes and explained what was going on and the interviewers seemed happy but wanted me to continue coding the full solution, error checking etc. Which in total took around 35 mins.
I was then asked how would I test this, what unit tests I would write etc. and afterwards they asked if I had any questions for them.

I was told in a previous email that the interview should last around 60-90 minutes and it did only last 60 minutes in total, but I am concerned as to why I wasn't asked a second programming question - is this a bad sign?
In my telephone interview I was asked two questions in 60 minutes so I assumed that I would be asked 2 or 3 this time, given I was told the phone interview would last 45 - 60 minutes.

I felt as though I solved the problem well, but the fact that we ended the interview early leads me to anticipate a reject.