I travel interstate several times a year. Each time I log in to LastPass away from home I get the email "Someone just used your master password to try to log in to your account from a device or location we didn't recognize" – fair enough. But LastPass seems to record the new location as my "new home"; so when I return home I get the same message again. Ok, twice each time I travel – once in the other state, and once when I get back to my real home.
BUT Even when I have been home for a while, in this case about a month since I confirmed that it was me logging in from the same place as I returned to after my last travel, I still occasionally get this message. I am using the same device and in the same location with the same internet provider as the last time I had to login to LastPass.