CeeCeeSix closed a deal for $450k

Although I've established a great relationship with this customer, the deal closed REALLY quickly for my world and that's why I feel like something is off with it...customer starts billing next month. Fingers crossed they're legit. After customer went through production, they have continued to add on additional products without wanting to test them. I'm obviously happy to be closing business but have a feeling that it might crash and burn and I'll have to deal with a gigantic chargeback. Seems too good to be true. SOS