I just had a new compressor installed in my heat pump. My heat pump compressor turns off (I can hear it) in air conditioner mode when the outside temperature is greater than 95F. The temperature inside the house rises quickly in the afternoons during these conditions. It works great when outside temperature is < than 95F. Is there a problem?

It sounds as if it is tripping on high pressure. This can be directly related to outdoor temp. Most residential a/c units will run a maximum capacity over 95 degrees. The compressor should not be shutting down though.

The best thing you can do, (short of hiring the company to come back), is making certain that the outdoor coil is free of debris. You should be able to see light through the coil fins. Also make sure that the indoor filter has been changed. Finally (with the outdoor breaker off) look at the fan blades on the exhaust motor. If they look cracked or uncentered then they could be your problem. Any further service should be done by a licensed technician because the other options are highly technical. I will list some of them here:

blocked or failed metering device (no or very low suction/high head)
kinked or obstructed line set (irregular pressures)
too much refrigerant (irregular pressures)
over amping exhaust fan motor (sometimes intermittent)
unmatched condenser to evaporator (corrected by Heat gain calc)
weak or failing capacitor (measured using special fluke style meter)