You can, although the sauce won't stay emulsified. This is not a huge issue for me, because I love leftover pasta in whatever way I can get it. Just know the sauce will mostly have soaked into the pasta and that some of your butter will be solidified in the bottom of your storage container. Just scrape it out and heat with the pasta, tossing to coat evenly. You can reheat on the stovetop or in the microwave in 30-second increments, tossing the pasta in between bursts.