If it was an extract batch and you followed the directions correctly, then my guess is that your OG was what it was supposed to be. The most likely scenario is that you didn't fully mix the boiled extract and top-off water giving you the low gravity reading. I've had that problem before and learned that I really had to give it a good mixing in order to get an accurate reading.
If you ever need to adjust in the future, I personally think that DME is the easiest way to go. Compared to a syrup, it's going to be easier to store, handle, weigh, and dissolve into water/wort.
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