The problem first started around the time I updated the plugin, so I thought it might be related. But, it turns out i have a customer who was placing a lot of orders and had two people logged in to their account at the same time on different computers. As they were placing orders at the same time on the same account, one of the orders would get overwritten and somehow an out of sequence order number would get assigned. I’m not positive, but this seems to be the root of the problem, I’ll keep observing to be sure.
Thanks for your help!