Good way to solve it, otherwise chanter is well in tune.
Hello Uilleannfinlander
How are your new set of pipes? Is it the new set that has the flat E,if so best get back to the maker !!!
RORY
Hi Mikko!
Just leave it like it is for the first week or two.
When I got my pipes and brought them back from Ireland it took about a good week or two before drones and chanter set in and accepted the Scandinvain climate.
The tenor drone almost died the first week but came back to life again.
Since then I haven’t touched my chanter reed, it has been very stable throughout both winter and spring. But this rainy summer has screwed it up a few times.
The drone reeds I have had to tinker with after that catapulting accident, but they have been ok since then. The tenor can be a bit week sometimes.
Would love to see some more picutures and a sound sample of your lovely new set 
/MarcusR
On my Gallagher concert and Angus D and B chanters, a flat E is a symptom of the reed being a little too open.
New chanter is abit different than my other one, and need some time to get used to it’s character. Ithink that lifting chanter off knee will solve problem quite well.
You might try rolling a staple with a larger bottom diameter.