I really don't think it is, I'm OCD about my machine and I peer into it on almost every job and I've never seen it glow red. Now I see it during daytime too. I ran it for 15 minutes this morning just to clean my own area rug and it was already glowing.
In the last 8 months of using it I've either A. Never Noticed it (which doesn't seem likely because it sticks out like a sore thumb) or B. Something is definitely restricted
I mean, I won't say that isn't possible Pete, but in the past 9 months of working with the machine I would had to not have noticed it. Like I said I'm OCD and I'm always listening to my machine and peering into it during jobs. My partner knows it's hard to get anything past me.
I asked him about when he uses the machine and he says it's only ever filled up to the cutoff float valve a few times. But maybe that's all it took to get a little gunk in there and cause a minor restriction.