That's called an event line and is more to do with a change of diet. Usually to do with them changing fields a few months ago, or going onto hay/haylage only, etc. It doesn't necessarily mean laminitis - although you should still be vigilant - and yes, they will grow out 
Rings are event lines, they mean something changed in the hoof growth rate, they can be caused by lami but even that is normally secondary to a dietary change. The rings start at the coronet band and grow down with the hoof, baring in mind the whole hoof takes 9-12 months to grow from coronary to the floor you can estimate when things have occurred. My best guess would be the bigger bottom line on your ponies hoof was 6-7 months ago (perhaps when you started stabling him for the winter and adjusted his diet? or perhaps it was the autumn flush of grass?) and the more recent line looks 1-2 months old (perhaps the spring flush? or increased turnout?).
If it were lami rings you normally see multiple rings which are significantly closer together at the heel than at the toe, where normal seasonal variations you tend to see they are straight and equidistant at the heel and toe and often you only get 1 significant line at a time. A horse on a really good stable diet won't get noticeable rings, but many horses in the UK do because of our fluctuating grass, as in just how much it suddenly flushes in the spring and autumn and also because many people drastically change ther horses diet in winter compared to summer.
I am sure if your pony had lami back when the lines occurred your farrier would have caught it and mentioned it during normal trims, if in doubt they are the best person to ask about it
If it were lami rings you normally see multiple rings which are significantly closer together at the heel than at the toe, where normal seasonal variations you tend to see they are straight and equidistant at the heel and toe and often you only get 1 significant line at a time. A horse on a really good stable diet won't get noticeable rings, but many horses in the UK do because of our fluctuating grass, as in just how much it suddenly flushes in the spring and autumn and also because many people drastically change ther horses diet in winter compared to summer.
I am sure if your pony had lami back when the lines occurred your farrier would have caught it and mentioned it during normal trims, if in doubt they are the best person to ask about it
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