Sorry you experienced this, Nuu. Panic attacks are horrible!
I think anxiety (and panic attacks) can develop anytime. We all know the strong relationship with drinking/withdrawal/early sobriety, but it can be triggered by a million things. I have life-long a history of anxiety and have had numerous panic attacks in my life. I started having them in my late teens in a period when I very rarely drank. The worst phase where I had very frequent panic attacks was much later, in my late 20's and they were related to my strong sensitivity and bad reaction to the sweetener aspartame (it's toxicity was not well-known back then). Of course I had hellish anxiety as a heavy drinker. Sometimes I think my anxiety (and milder panic attacks) are hormonal, I tend to get them as PMS symptoms, but not always.
Since these symptoms are generated by changes in our brain chemistry, many things can be triggers, including food additives, medications, and physiological or emotional fluctuations we are not aware of easily. I just recently had some pretty bad anxiety when taking an antidepressant, prescribed for anxiety primarily, and while it's normal that they often increase anxiety at first, mine made me pretty unstable and up/down even after 5 weeks, so I stopped it.
Maybe yours was indeed at least in part related to your bad mood and the fears that you have mentioned. If it's something that bothers you, I would try to sort it out somehow. I think new and unexpected challenges can increase anxiety in everyone. I find that the best remedy for it is exercise.
I know quite a few people who developed anxiety and occasional panic attacks later in life, totally unrelated to drinking or any drug use. My dad started having this in his 70's, for example, and apparently never before.
I hope it was a one-time event for you!