I have noticed this too. I take great care to make sure to pick the parts with the little van by them; it shows one shipping location until I go to check out and suddenly there are two or more. I would agree it’s an algorithm or something. I doubt it’s intentional. So I emailed them this question and someone called me a few hours later. He said it is likely due to their shipping algorithm deciding that it's less expensive to split the shipment and ship from two warehouses, for example if a part can be shipped for less from a warehouse closer to the orderer rather than lumped in with the other parts and sent from the further warehouse. He said next time it happens to send a screenshot so they can look into it. He seemed genuinely interested in seeing if there's a flaw somewhere and correcting it.