I LOVE that pattern. My probooster is also from NBD so we got the all grey mystic pattern (which is fine by me, goes with my van's grey interior, but I know Ruthie would prefer color... but the fact she still prefers that booster over any other tells me it's the best for her)
And I still check Ruthie's tightness (I moved her behind me so when the kids are all getting in the car, she can get in on my side and the boys don't have to wait for her to get in and they can deal with the sticky door that she can't open or close on her own (she can with the one on my side) and now I've taken to buckling her and she gives me this face sometimes... like "Mommy, you know I can do it myself", but she's my baby. I make Jeffrey still check her seatbelt being tight in her dad's car since it's a 2-door (she's behind the driver so he can have the extra leg room on the passenger side there) and he's just happy I'm not nagging him in my van about it)
I don't think we ever stop worrying, though. I still ask the boys and turn around to look at their seatbelts to make sure they are wearing them and they are snug. Damian has taking to responding with... "Mom, you know I always put my seatbelt on" but Jeffrey is a little sassy and last time said... "Mom, I know how to use a seatbelt, I always use a seatbelt, I've never ridden without a seatbelt, except when I was in a carseat. I'd tell you if I wasn't buckled yet!" LOL... he's my safety conscious one so he can get away with it (the other day at the park he kept pointing out every single person/kid without a helmet riding a scooter/bike/skateboard and telling me they weren't safe. I wish I could have done something other than agree with him and remind him why I make the kids wear them, but there you are.