I have a heat pump which appears to be working normally. In the heat mode, and the outside temperature about 45 degrees, and the unit running for about 20 minutes, I checked at the indoor air hander the tubes going into/out of the evaporator coil. The larger tube was too hot to hold, the smaller tube was cool to the touch... perhaps I'd suggest maybe about 70-80 degrees. I was surprised there was such a temperature drop in and out of the evaporator coil. Is this normal?

Thanks, Tom

Yes in the heat mode you are removing heat from that coil and blowing it into the house. The better the temperature drop between these sections of coil the more heat that is being transferred.