My 5 yr old Lennox SignatureStat thermostat had about 6-8 very dark blue vertical lines over an inch of the display. It was not possible to see anything where the lines were. I pressed menu, went in a few options, the lines were always there. I walked away and came back 2-3 hours later and the lines were gone.

Is this sign of an early death for my t-sat? Should I wait longer or have it changed VERY soon? I see this t-sat is not manufactured anymore. What would be an excellent replacement?

Thanks for your help and advice.