I've done that and once when taking my parents' car to a quickie lube place (Jiffy Lube where I could witness everything from the waiting area) I noticed that they also wrote down the date and mileage on the filter. I've also done this with air filters. I try to keep a log of maintenance on my computer, but sometimes I forget to note it. I always take a photo of my odometer and the supplies used, and usually can track the date down if I forget.