Windsor yeast activity unusual?

Did a Newcastle all-grain kit from Austin Homebrew which came with Windsor dry yeast as my option. Brewing session went well, OG (1.053) right on the mark. Fermentation started vigorously within a couple of hours and slowed down as normal after a couple of days. Transferred to a secondary after 6 days, with gravity reading of 1.030. Took another reading after another 6 days with a reading of 1.025. Activity has been very slow, but not stopped during this period. Over the last 7 days activity in the bubbler has significantly picked up, closer to what it was on about the 3rd day after pitching. I've not seen this before, and while I understand Windsor to be a bit slower with lower attenuation, and while I'm anxious to hit a FG of closer to 1.011 per the recipe, does this "renewed interest" on the part of the yeast indicate normal activity, or am I looking at something nefarious? Frankly, the only other yeasts I've used are Nottingham and S-04 and never saw fermentation pick up like this after almost 3 weeks (3 -4 bubbles a minute).

What temp are you fermenting at? What was your mash temp? I, myself, have not had much luck with windsor. Seems it likes a low mash temp to attenuate well.

Also 6 days seems pretty early to transfer to 2ndary especially with a gravity stil at 1.030. Most people don't even use a 2ndary unless adding fruit, oak,etc. I think maybe the early move may have stalled the fermentation and now it's starting back up again

Mash temp was 152. Fermenting temp around 67.

Yeah that's odd, those numbers are pretty much right in check with fairly good attenuation. Maybe the move so early to 2ndary was just too soon.

If that's the case, that's a relief. I bought the kit based on the reviews, and I've been struggling with finding a decent brown ale recipe. After some iffy results, I'm hoping this comes in good. Everything went great on brew day.
I'll just wait 'til the gravity gets down to where it should be.

It appears you racked before fermentation was done and now its picked up again. Let it go for as long as it needs to. It is possible, as you suggest, that there is an infection, but if that is the case, there's nothing to be done about it now.

I use Windsor in two beers that I think it works really well in - a cream stout and an english ale with honey. Both have placed at competitions.

Highly doubt infection if you racked @ 1.03.... Still lots of work to be done there. You didn't mention anything looking like an infection. Racking probably just stirred it all up and gave it a bit more o2 to finish the job. Don't think you hurt anything by racking early... Might have just sped things up ;-)

I don't think you "hurt" anything by moving it, but i do think a better choice would have been to let it ride in primary until you were ready to bottle. IMO 2ndary really is not needed, but if you're going to do it wait until primary fermentation is done and verified by a gravity reading.

Windsor has always given me a biphasic fermentation (two active periods separated by a lull of 3-5 days). Its so pronounced that I actually wrote Lallemand suggesting that their Windsor “strain” might actually be two very unequal populations with the minor one more attenuative than the other. They did not like that idea much. One alternative is that Windsor makes a product during the initial fermentation that inhibits growth/metabolism halting fermentation and creating the lull. The hypothesis would be that this product breaks down spontaneously over time allowing a second round of growth fermentation. Other explanations are possible.