Not seen before-normal?

I have been brewing for 2years now - still a beginner. After bottling, I wait a week and give my bottles a swirl to mix up the yeast then let em set for a month total. The yeast has always been very fine, powder like when mixing - sort of milky like on the bottom of the bottle. The yeast in my current batch is clumpy and not fine like my other brews. Should I be concerned? And why the difference? The beer is an AG Special Bitter and the yeast was Wyeast 1099 Whitbread Ale Yeast. This is the first time that I used this particular yeast.

Wyeast 1099 is a very highly flocculating yeast, that is probably why it is forming in clumps like that.