MacBook Air Battery capacity down to 93%! Should I worry?

The battery is already more than 2.5 years old from the manufacture date and even though the machine was used occasionally as you mention in the question, the battery will still degrade over time - just not as fast as with charging and discharging every day.

The storage temperature and battery charge also determine how quickly the battery degrades when stored for longer periods of time. This is mentioned on Apple's own website.

Do not fully charge or fully discharge your device’s battery — charge it to around 50%. If you store a device when its battery is fully discharged, the battery could fall into a deep discharge state, which renders it incapable of holding a charge. Conversely, if you store it fully charged for an extended period of time, the battery may lose some capacity, leading to shorter battery life.

Lastly, I find from personal experience that the design capacity indicator fluctuates with the charge currently in the battery. On my 2018 MacBook Pro, there is about a 2 percent when the battery is nearly full charged vs nearly empty.

In conclusion, I would say there is no need to worry about it.

Being at 93% after two years of regular use is relatively normal and, echoing what thejunejaster has said, is nothing to worry about.

Batteries will degrade over time, as previously mentioned, regardless of use if not storing them in optimal conditions. For reference, a 33 cycle count would be extremely low (but expected given your use of the machine), and Apple recommends getting the battery serviced at 1000 cycles.

That being said, I'm at roughly 650 cycles on my 2014 MacBook Pro 15" and my battery health reads 86%. I've also had mine serviced sometime roughly two or three years ago, so that's expected. I'd recommend keeping an eye on it over the course of the next year to see if it dips low quickly, but if it ever becomes a genuine concern you are welcome to make an appointment at your nearest Apple Store for a battery service (I believe mine was $200, and they replaced the bottom of the enclosure as well).

Hope this helps.