Yes, it does happen, quite frequently, with DAS. It is 'growing up' from producing juvenile foliage (the usual DAS foliage is just like the foliage on a one-year-old White Spruce seedling) to adult foliage. The only way to stop it is to prune the shoots out. Though personally, I think the adult foliage is nicer, so if I had a DAS I'd leave it to turn to an adult ;-)

Resin

DAS = picea glauca 'conica' ....

which came from Picea glauca ....

it is reverting to Pg [or maturing as noted]... if it has the same steel blue green foliage ...

Pg is a lumber/paper tree .... research its growth rate ... we are talking serious forest tree here [why resin prefers it, no doubt]... it will swamp the deck.. rather quickly.. compared to conica anyway ...

ken

"we are talking serious forest tree here [why resin prefers it, no doubt]..."
Yeah . . . though Picea glauca isn't really a 'serious' forest tree, maybe call it an amateur one ;-) It doesn't grow particularly fast nor get very large. Maybe 4m in 10 years, and mature height typically 15-20m, rarely a bit more. Only about a quarter or a third of the growth rate of Picea sitchensis, a bit over half to two thirds that of Picea abies.

Resin

i picture a deck .. with a stairway .. and cute little 4 foot plants guarding each side.. growing 2 to 4 inches per year ..

i then picture mine doing the same thing.. with its 8 to 12 inches of growth this spring ....

tree or deck ... i presume you have much more invested in the deck...

i would leave it.. as i have mine.. out 200 feet from the house .. its a cool talking point on conifer tours ....

but not something you want to leave next to the deck ....

but in reality.. you probably have 5 years to figure out what to do with it.. before it starts taking over the deck

ken

Although small ones can be had cheaply if of any size when purchased the 'Conica' probably cost quite a bit more than a typical seedling might have. More will have been paid for the vegetatively propagated cultivar, so letting it revert to the typical growth would be throwing away the extra money spent to get the dwarf compact form. And it take years for such reversions to overwhelm and kill the original dwarf growth, an ugly effect prevailing until then.

Japanese cherry trees grafted on sweet cherry and older hybrid rhododendrons grafted onto Rhododendron ponticum are frequently seen here with the rootstocks having been allowed to grow up through and surpass the fancier named varieties stuck upon them. Sometimes when these are asked about and it is advised that the rootstock sprouts be removed the reply is that they are going to keep them anyway. This seems like a pretty bad idea, especially considering how much grafted Japanese cherry trees cost (grafting of hybrid rhododendrons is no longer common). Sweet cherry is pretty much a weed species here, if someone set out to get an unselected seedling (or rootstock cultivar, if any are being used) of this they could get it a lot more cheaply than buying a grafted cherry tree.

"so letting it revert to the typical growth would be throwing away the extra money spent to get the dwarf compact form"

But price wouldn't be relevant to me, as I'd never buy one of the dwarf ones . . . the only way I'd get one was if I inherited it in moving to a new house - if that happened, I'd gladly let it revert ;-)

Particularly as typical Picea glauca is very hard to find over here, too.

Resin