I just purchased a pair of Genalex KT66 and I set the bias on my Marshall Bluesbreaker RI to its lowest lever prior to installation. When I turned the amp on one tube was 45.6 and the other 42.3. Again, this is at its lowest bias settingl. My valves in there before (another set of GEC KT66) was 40 and 38.9 at a mid range. Should this be a concern, or just that the tubes are running hot and will burn out quicker? Thanks for any help.