In any of our heat exchanger or dual boiler espresso machines that use a pressure stat it's normal to sometimes experience a big steam boiler pressure drop when the valve is opened for the first time in a day. This is a normal function caused by the machine's initial pressure build creating "false pressure" in the boiler when the boiler goes from not pressurized and open to pressurized and sealed. The solution is to simply open the steam valve once the machine is warmed up, as this will relieve the false pressure and allow the pressure stat to sense the true pressure of the boiler (you can also try doing this the night before when the machine is cooled off). The machine should heat back up to full pressure rapidly.
This can also be incorporated at the beginning of your drink making routine to avoid delays. When you approach your warmed up machine (tip: use a timer to have the machine warmed up when you want), open the steam valve first to "wake the boiler up", run 2oz of hot water through the group head and portafilter into your cup or shot glass (to ensure everything is toasty warm), and then prep your milk pitcher, grind your coffee and make your favorite drink.