Your question is very confusing. Are you saying the tacho meter (or is it a Hobbs meter) is showing exactly 1 hour but the engine has been running for 1hour 15minutes (1.2 hours)?
The time in your Pilot log book (or are you talking about the airframe log book?) should be the time you ACTUALLY spent in command of the aircraft whilst it was under it's own power. This would include taxi times as well as airborne time.
Does you engine meter (of what ever type it is) record the engine running time? If it is a Hobbs meter type it may not start recording until you exceed a threshold airspeed (usually about 40 knots) so that it records airborne time, rather than engine running time, for the airframe log book.