Low iron is common and usually corrects itself. Honestly, I wouldn't do a darn thing other than maybe increase your own iron levels through diet. The drops are nasty and cause a lot of constipation, which can lead to other issues with your baby.
Find out what the exact number was from your baby's test and from there research what normal and low ranges actually are. If your baby is just on the low end of normal, or the high end of low, you may very well be able to correct this with diet.
The kinds of things you read about are for babies with critically low iron over an extended period of time.
Kellymom.com is a great resource for info about this. Supplementing with iron or iron-fortified foods can interfere with your baby's normal absorption of the lacto-ferrin that's in your breastmilk. A baby's digestive tract has receptors that fit uniquely with the iron in breastmilk, which has a different shape than the synthetic iron in supplements and iron-fortified cereals and formulas. Synthetic iron doesn't fit into those receptors, so much more iron is needed in foods that have synthetic iron than is present in breastmilk, because the iron in milk is absorbed to much better. If you introduce synthetic iron, you can clog up those receptors and the easy bond between the iron in your milk and your baby's digestive tract is compromised. It's not the end of the world, and something that happens eventually as you move your baby to table food and away from breastmilk, but it's something that is worth putting off if you can. I didn't know about this with my oldest son, supplemented him with iron-fortified formula and cereal and we had trouble maintaining his iron levels after that even though I was breastfeeding and my iron levels were fine at the time. I avoided synthetic iron with my younger kids and their iron levels stayed optimal just on breastmilk.
Anyway...don't freak out about this. Add some iron-rich foods to his diet and yours and have him re-tested at his next visit and see if he's moving in the right direction.
FWIW, truly low iron (anemia) is very common and reversible. I've had bouts of low iron throughout my life and it's always been something I've been able to correct with diet.
Really...it's not a big deal and your baby will be fine. This just means that right now, dietary iron is something to pay attention to.