Sometimes different sun, fertilizer, or soil quality can lead to different colorations in blooms. Your white 'Sterling Silver' might have altered a bit in the year since planting depending on conditions.

I have several dahlias planted in far different areas of the yard and different soils that bloom pink vs lavender, medium red vs dark red etc. I don't know anything else that would affect your blossom color if you have planted the same tubers as originally purchased.

Big and beautiful foliage rules~ Congratulations!

Well, my flower bed is about 4 yrs old. Every year I keep adding soil. The only thing done differently this year as opposed to past years, is I've been using the Miricle Grow on all my plants. The big KABOOM happend (after I was quite worried that NONE of my tubers were taking and it had taken them alot longer)
This year I actually had to stake one of my Daliahs! (past I hadn't due to height being not all that tall) and this year, holey dynomite!!! Just awsome!
I was always under the impression that they needed more of a full sun. Where I have my girls planted, they get the first thing in the morning sun and in the afternoon they're in the shade (and well watered)

Anyways, back to the main question. I've asked my mom and a friend of mine who is an avid planter of ALL sorts. Neither of them have ever heard of it. They just said "the tuber is the tuber. It shouldn't change colour at all"
But who knows???

I've noticed slight variations in colour dependent upon where it's planted.

Mine like sun, but also relief from the hot afternoon sun. At least 6 hours is good. I also find that if they have to work a little to get more light, they will grow taller.

We used to grow Sterling Silver & it always had a hint of Lavender on it's tips.