Hi, Litecoin Dev here.
It's not an issue to worry about. Essentially what's happening is, certain mining pools were manually setting their BIP9 version bits to signal support for SegWit. And since SegWit has been activated, no such soft fork is being deployed with the same version bits as SegWit. Thus the client thinks that it might be outdated since it doesn't recognised any soft fork being 'triggered'.
We're working with the remaining pools who haven't stopped signalling to stop. AFAIK, these pools are F2Pool (Discus Fish) and Batpool.