If I'm reading it right, there have been several reports over the last few days of similar errors in logs in the TS newsgroup -- in almost all cases there was no obvious problem with the connection and TS asked users to keep an eye on their logs and report it if the errors continued. (Presumably they're meaning "days" rather than hours!)
For instance, in thread ("Modem Reboot, now strange log...."), TS writes:
"I have checked your connection from our side and everything appears fine
with your modem & signal levels and the network looks fine too. The T4 error
in your logs, can indicate issues with the modem. I would advise you to keep
an eye on your modem logs to see if you keep getting any more of these types
of errors. If they appear to be occurring often, then this will require a
tech visit."
hth