Treasures

Evie is into collecting things BIG TIME.
Her newfound hobby is cute and not at all troublesome except she's begun collecting "like" objects. I don't know if I should rejoice that she is this smart and particular about what she grabs. Or, should I be freaking out and researching autism?
Evie started actually collecting things in the last few weeks (more than just picking up oddities and shoving them in her mouth, she would pick something up and carry it around with her). She started by picking up one of my round rocks out front. She carried it around the side of the house and back again. This went on for a good while. The average person would have lost interest after carrying the rock to its new home but she carted this thing back and forth a few times (ok, a near dozen) before I put it away for fear it would drop and break a toe.
Then she started picking up sticks. At first, any stick was fascinating. Very recently I noticed all the sticks were about the same size. She carried them in a tight fist (her right, which is worth noting because I swear she is right-handed) while gathering more with her left hand. She will carry things like this until we wrestle them away and distract her with other objects. She does, typicaly, return to gathering what she began collecting moments before.
At our picnic, she took all 4 carrot sticks and carried them around while munching away.
At home, she will carry multiple objects that are small and unsimilar (since she doesn't have multiples of anything) like a Mr. PotatoHead arm, one light-up bouncey ball, a tupperware lid and, of course, moo-cow. She will carry these things off and on throughout the day. We put them on the table while she eats and then she grunts to have them back when she is done.
While downtown on Brown's Island, she gathered rocks. She would also gather long grass blades and switch between the two passions. She kept one rock nearby throughout the entire day before losing it to the river (I showed her how to throw rocks in the water and she mistakingly chose her prized rock. Lesson learned: throw things in the river and they will not come back).
One girl at the Richmond 'Zine Fest recommended that I get her a bag to carry all her prizes in.
I'm actually considering it.
I'm getting a little concerned though when she noticed she had 2 of the same pink bath toys. She played with these two and wanted to carry them around the house when we were done. She's smart - she knows what matches. But, is this good?
Is this a milestone or is my kid just a nerd?