Overboosting after car sits for a few days

Last week I went on vacation and left my 08 STi in the garage for 4 days without being driven. A couple weeks ago I got tuned via OpenSource for the following mods: TBE, EL Headers, Intake, MAC EBCS, and DW65. The tune felt great and I had been hitting the target boost of 19psi in the 3rd and 4th gear pulls that I had done. After letting the car sit for 4 days I drove it and did a 3rd gear pull and hit 22psi for about a second then it dropped down to 19psi and held. Then I did a 4th gear pull and it hit around 23-24psi for a second then dropped down to 19psi. After that, every pull I did hit the target 19psi. The weather conditions were the same as when the tune happened.

Basically I was just wondering if this is normal when you let the solenoid sit for a few days right after it is installed. Or if the solenoid needs to be broken in? It doesn't sound right but i'm just throwing out some opinions. Please let me know what you think.