Okay, here is the quick version of the history
35k- car purchased

36k- tranny fluid drain and fill/replacing the pan/gasket (don't know if the magnets were cleaned) I had it done by a lube place. It was replaced with Castrol

After having this done, the car shifted MUCH better/smoother. It was really great. Now about 10k later, the shifting is not as great as before. second to third does not have grippy feeling- almost like a slight slip. SHould I do another drain and fill, have them clean the magnets? Stumpped. The car now has about 46k. TIA